Programme and Slides

All the talks will take place in the room Y15 G20. Just follow the signs.
Additionally, there will be a transmission into Y15 G19 and a live stream on youtube.
Please find also the slides and youtube recordings if already available in the list of talks / posters.

• Timetable
• List of Talks and Slides
• List of Posters and PDFs
• Contributed Sessions and Organizers
• Conference Dinner

Timetable

Mouse over for details

(might still slightly change)

List of Talks and PDFs

Click on the right hand side to download a pdf version of the slides or to see the recording where available. If you cannot see youtube videos for some reason please let me know and I'll upload the videos elsewhere.
Speakers please upload a pdf version of your talk in the user center.

Monday 5th of September 2016

Chairperson: M. Colpi

• 09:00 – 09:30: S. Vitale [ slides ] ‹ The LTP experiment on LISA Pathfinder and its first results ›
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  Stefano Vitale University of Trento, Italy The LTP experiment on LISA Pathfinder and its first results

• 09:30 – 10:00: K. Dooley [ slides ] ‹ Advanced LIGO: news from the dark universe  ›
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  Katherine Dooley University of Mississippi Advanced LIGO: news from the dark universe After over 50 years of effort, scientists and engineers recently succeeded in the challenge to measure the infinitesimal changes in the separation between two mirrors caused by cataclysmic events in the distant universe. During its first observing run in fall 2015, the Advanced LIGO interferometers witnessed the passing of gravitational waves created by the collisions of black holes over 1 billion light-years away. These first and second detections of gravitational waves bring to life a new instrument for astronomy, delivering news from the otherwise invisible affairs of the cosmos. I will describe the Advanced LIGO interferometers, the detections that have been made, and the outlook of ongoing and planned instrument work to further improve Advanced LIGO's sensitivity for future observing runs.

• 10:00 – 10:30: B. Schutz [ slides ] ‹ LIGOs Black Holes and Science in the LISA Era ›
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  Bernard Schutz Max Planck Institute for Gravitational Physics LIGOs Black Holes and Science in the LISA Era

• 10:30 – 11:00: Coffee Break
• 11:00 – 11:30: P. McNamara [ slides ] ‹ LISA Pathfinder: First steps to observing gravitational waves from space ›
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  Paul McNamara European Space Agency LISA Pathfinder: First steps to observing gravitational waves from space

• 11:30 – 12:00: M. Hewitson [ slides ] ‹ In-flight Performance of the Optical Metrology System on LISA Pathfinder ›
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  Martin Hewitson AEI Hannover In-flight Performance of the Optical Metrology System on LISA Pathfinder

• 12:00 – 12:30: W. Weber [ slides ] ‹ Physical model of the LISA Pathfinder differential acceleration measurement and its application to LISA ›
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  William Joseph Weber Università di Trento / INFN Physical model of the LISA Pathfinder differential acceleration measurement and its application to LISA

• 12:30 – 13:00: K. Danzmann [ slides ] ‹ The Status of LISA ›
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  Karsten Danzmann AEI Hannover The Status of LISA

• 13:00 – 14:30: Lunch Break

Chairperson: O. Jennrich

• 14:30 – 14:50: J. Martino [ slides ] ‹ On-flight characterization of Coldgas micro-Newton thrusters for Lisa Pathfinder ›
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  Joseph Martino APC On-flight characterization of Coldgas micro-Newton thrusters for Lisa Pathfinder The micro-Newton ColdGas thrusters are used on LISA Pathfinder for attitude control and orbit manoeuvre to maintain the spacecraft on a Lissajous orbit around L1. But more importantly they are one of the key hardware components to achieve an almost perfect drag-free control of the spacecraft during the science runs. The drag-free strategy consists on forcing the satellite to follow the test Masses. Any external non gravitational disturbances like Solar Wind will appear as differential forces or torques on the Spacecraft relative to the Test Mass. In the drag-free scheme, the ColdGas Thrusters are used as the actuator in a closed loop system to compensate these forces with a mean thrusts around ∼ 9uN. The quietness of a space environment allow us to investigate the thrusters performance such as noise, gains and stability to an unprecedented level down to very low frequencies (0.1mHz). By using the overall mission nominal thrusts, one can monitor the thrusters noise and the Solar Wind DC pressure on the satellite. A dedicated experiment : simultaneous injection of out of loop forces at different frequencies per thrusters allowed us to constrain the thrusters gains within 10%.

• 14:50 – 15:10: M. Nofrarias ‹ Magnetic force noise in LISA Pathfinder ›
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  Miquel Nofrarias Institut d’Estudis Espacials de Catalunya (IEEC) Magnetic force noise in LISA Pathfinder The differential acceleration measurement between two free-falling test masses on-board LISA Pathfinder is limited in the low frequency regime by force noise applied to the test masses. Several effects can contribute as force noise on the inertial masses and, among them, magnetically-induced forces are precisely one of these effects limiting the perfomance of the instrument in the millihertz band. The origin of this disturbance is the coupling of the residual magnetisation and susceptibility of the test masses with the environmental magnetic field. In order to fully understand this term of the noise model, a set of coils and magnetometers are integrated as a part of the LISA Pathfinder diagnostics subsystem. During the operations period a sequence of magnetic signals were induced by the coils producing an associated force on the test mass. Here we report the analysis of these investigations and the derivation of a magnetic contribution to the differential acceleration noise budget.

• 15:10 – 15:30: L. Ferraioli [ slides ] ‹ The LISA Pathfinder GRS Front-End Electronics ›
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  Luigi Ferraioli ETH Zürich, Institut für Geophysik, Sonneggstrasse 5 8092 Zürich The LISA Pathfinder GRS Front-End Electronics The detection of gravitational waves in space at frequencies as low as 0.1 mHz requires a gravitational reference sensor (GRS) of unprecedented capabilities in terms of residual acceleration. The GRS Front-End Electronics (GRS FEE) is the electronic system used to sense the motion of a test mass (TM) with respect to the spacecraft and to actuate it along the controlled degrees of freedom. The TM is surrounded by the electrode housing that holds twelve sensing/actuation electrodes corresponding to six sensing channels per TM. Such a scheme provides the readout for the TM displacement and rotation along all degrees of freedom. We provide an overview of the LISA Pathfinder GRS FEE design and we report on the instrument in-flight performances.

• 15:30 – 15:50: D. Vetrugno [ slides ] ‹ The $\Delta g$ workflow: from measured displacements to the differential external acceleration. ›
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  Daniele Vetrugno University of Trento The $\Delta g$ workflow: from measured displacements to the differential external acceleration. The main scientific products delivered by LISA Pathfinder satellite are the differential external acceleration, $\Delta g$, and its power spectral density, $S_{\Delta g}$. In this talk, the full procedure to get $\Delta g(t)$ will be presented. Starting from the raw measured time-series, we will review the data manipulation and the physics of the conversion into $\Delta g$. Then, we will concentrate on the main features which affect $\Delta g$, from the centrifugal force at low frequencies to the events and glitches during the measurements. Finally, we will talk abut the time evolution of $\Delta g$ from the starting of the operations till 26/06/2016, the LTP/DRS handover.

• 15:50 – 16:10: A. Wittchen [ slides ] ‹ Coupling of relative intensity noise and pathlength noise to the length measurement in the optical metrology system of LISA Pathfinder ›
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  Andreas Wittchen AEI Hannover Coupling of relative intensity noise and pathlength noise to the length measurement in the optical metrology system of LISA Pathfinder LISA Pathfinder is a technology demonstration mission for the space-based gravitational wave observatory LISA. It demonstrated that the performance requirements for the interferometric measurement of two test masses in free fall can be met. An important part of the data analysis is to identify the limiting noise sources. This measurement is performed with heterodyne interferometry. The performance of this optical metrology system (OMS) at high frequencies is limited by measurement noise. One such noise source is Relative Intensity Noise (RIN). RIN is a property of the laser, the photodiode current generated by the interferometer signal contains frequency dependent RIN. From this electric signal the phasemeter calculates the phase change and laser power, the coupling of RIN into the measurement signal depends on the noise frequency. RIN at DC, at the heterodyne frequency and at two times the heterodyne frequency couples into the phase. Another important noise at high frequencies is path length noise, to reduce the impact this noise is suppressed with a control loop. Path length noise not suppressed will couple directly into the length measurement. The subtraction techniques of both noise sources depend on the phase difference between the reference signal and the measurement signal, and thus on the test mass position. During normal operations we position the test mass at the interferometric zero, which is optimal for noise subtraction purposes. This talk will show results from an in-flight experiment where the the test mass position was changed to make the position dependant noise visible.

• 16:10 – 16:30: S. Paczkowski [ slides ] ‹ Laser frequency stabilisation and interferometer path length differences on LISA Pathfinder  ›
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  Sarah Paczkowski AEI Hannover Laser frequency stabilisation and interferometer path length differences on LISA Pathfinder The LISA Pathfinder mission is a technology demonstrator for a LISA-like gravitational wave observatory in space. Its first results already exceed the expectations. This is especially true for the optical metrology system whose performance is more than a hundred times better than on ground. To suppress the effect of laser frequency noise on the optical readout a nested feedback control loop was implemented. It's sensor is the so-called frequency interferometer which has a deliberate path length difference to assess the frequency noise. However, with the extremely low total noise in the differential interferometer, there is a small coupling from frequency noise into the differential readout remaining. In dedicated experiments, we increase the frequency noise via modulation. From this coupling the optical path length difference between the measurement and the reference beam in the measurement interferometers can be estimated. In this talk, we present the results of the dedicated loop characterisation and arm length mismatch experiments as well as long term estimates.

• 16:30 – 17:00: Coffee Break
• 17:00 – 17:20: R. Giusteri [ slides ] ‹ The free-fall mode experiment on LISA Pathfinder: first results ›
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  Roberta Giusteri Università di Trento / INFN The free-fall mode experiment on LISA Pathfinder: first results The LPF space mission is testing the critical experimental challenge for LISA by measuring the differential acceleration between two free-falling test masses inside a single co-orbiting spacecraft at a level of sub-femto-g for frequencies down to 0.1mHz. In LPF it is necessary that one test mass (TM) is electrostatically forced to follow the orbit of the other TM. This force represents a noise source in differential acceleration at frequencies below 1mHz. The free-fall mode experiment has been performed in order to reduce this source of noise: the actuation is limited to short impulses on one TM, so that it is in free fall between two successive kicks, while the other TM is drag-free. The free-fall mode thus provides a different technique for measuring the differential TM acceleration without the added force noise and calibration issues introduced by the actuator. Data analysis challenge is related to the presence of the kicks: they represent a high-noise contribution and need to be removed, thus leaving short gaps in data. In this talk we present data of the LPF free-fall measurement campaign and summarize the results obtained by several analysis techniques.

• 17:20 – 17:40: P. Wass [ slides ] ‹ Electrostatic test-mass force-noise disturbances as measured by LISA Pathfinder  ›
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  Peter Wass Imperial College London Electrostatic test-mass force-noise disturbances as measured by LISA Pathfinder We report on measurements made to characterise the electrostatic forces acting on the free-falling test masses of LISA Pathfinder. The most significant of these arise from the test mass charge-to-force coupling through stray electric fields in the gravitational reference sensor and the effect of the random charge build up due to cosmic rays. We show that both effects can be suppressed by a combination of test-mass charge control and electric-field compensation.

• 17:40 – 18:00: R. Dolesi [ slides ] ‹ The contribution of Brownian noise from viscous gas damping to the differential acceleration noise measured in LISA Pathfinder between two nominally free falling test masses  ›
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  Rita Dolesi Università di Trento/INFN-TIFPA The contribution of Brownian noise from viscous gas damping to the differential acceleration noise measured in LISA Pathfinder between two nominally free falling test masses The Brownian noise associated with residual gas viscous damping of the test mass motion in a restricted geometry is expected to be among the major noisy force sources limiting the free-fall purity of the test masses in a LISA-like observatory. In this talk we describe how in LISA Pathfinder we obtain an estimation of the residual gas pressure by measuring the radiometer effect with dedicated in-flight thermal gradient experiment. These pressure values, together with considerations on the residual gas composition, allow us to derive an estimation of the gas damping Brownian noise contribution to be compared with the frequency independent component of the noise measured in LISA Pathfinder. Possible improvement in the gas damping Brownian noise suppression strategies for LISA will be discussed.

• 18:00 – 18:20: C. Trenkel [ slides ] ‹ The engineering of LISA Pathfinder – the quietest laboratory ever flown in space ›
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  Christian Trenkel Airbus D&S UK The engineering of LISA Pathfinder – the quietest laboratory ever flown in space We review the engineering approach adopted to ensure the required gravitational, magnetic, thermal and residual acceleration stability on-board LISA Pathfinder, and present the in-flight results that have been achieved. Arguably, this stability makes LISA Pathfinder the quietest laboratory ever flown in space. The implications for LISA and other applications are discussed.

• 18:20 – 18:40: W. Klipstein [ slides ] ‹ LISA-derived Flight Phasemeter on the GRACE Follow-On Mission ›
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  William Klipstein Jet Propulsion Laboratory LISA-derived Flight Phasemeter on the GRACE Follow-On Mission GRACE Follow-On will replace the Gravity Recovery and Climate Experiment (GRACE) mission, which has been measuring Earth’s gravity field since 2002. Like GRACE, GRACE Follow-On will use a microwave link as its primary instrument to measure micron-level changes in the 200km separation of a pair of satellites in a following polar orbit. GRACE Follow-On will also include a 2-way laser-link, the Laser Ranging Interferometer (LRI), as a technology demonstrator package. The LRI is an NASA/German partnership and will demonstrate inter-spacecraft laser interferometry based on LISA technologies at the predicted level below 30 nm/√(Hz) between 10 and 100 mHz, limited by laser frequency noise in the single-link configuration. This talk will give an overview of the LRI phasemeter developments as they relate to LISA

• 18:40 – 19:00: P. Laufer [ slides ] ‹ MEMS Ion Thruster Chips to Significantly Enhance Cold Gas Thruster Lifetime for LISA ›
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  Philipp Laufer Technische Universität Dresden MEMS Ion Thruster Chips to Significantly Enhance Cold Gas Thruster Lifetime for LISA Micropropulsion is a key component for ultraprecise attitude and orbit control required by the eLISA mission. LISA pathfinder uses cold gas microthrusters that are accurate but require large tanks due to their very low specific impulse, which in turn limits the possible mission duration of the follow up eLISA mission. Recenty, we developed a compact MEMS ion thruster on the chip with a size of only 1 cm2 that can be simply attached to a gas feeding line like the one used for cold gas thrusters. It provides a specific impulse greater than 1000 s and only requires a single DC voltage. Since the operating principle is based on field emission, very low thrust noises similar to FEEP thrusters are expected but with gas propellants. The MEMS ion thruster chip could be mounted in parallel to the existing gold gas system providing high Isp and therefore long mission durations while leaving the cold gas system in place. To enable a possible mission extension, the MEMS ion thruster could take over from the cold gas system as a backup while maintaining the existing micropropulsion thruster system with its heritage therefore minimum risk.

• 19:00 – 19:20: M. Tinto [ slides ] ‹ Enhanced Gravitational Wave Science with LISA and gLISA ›
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  Massimo Tinto Jet Propusion Laboratory Enhanced Gravitational Wave Science with LISA and gLISA The geosynchronous Laser Interferometer Space Antenna (gLISA) is a gravitational wave mission concept that has been studied during the past four years at JPL in collaboration with scientists at INPE (Brazil) and Stanford University. It entails three drag-free satellites in a geosynchronous trajectory resulting in a triangle formation of arm-length equal to 73000 km and an observational frequency band that is “blue-shifted” with respect to that of LISA by about a factor 70. Because of the complementarity of the observational bandwidths and sensitivities of the two missions, their joint operation will result in an enhanced scientific return over those obtainable by each observatory operated as stand-alone.

Tuesday 6th of September 2016

Chairperson: P. McNamara

• 09:00 – 09:30: F. Ricci [ slides ] ‹ Advanced VIRGO: State of the Art ›
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  Fulvio Ricci Università La Sapienza; Roma Advanced VIRGO: State of the Art

• 09:30 – 10:00: C. Belczynski [ slides ] ‹ Evolutionary predictions in the advanced LIGO/Virgo era ›
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  Chris Belczynski Evolutionary predictions in the advanced LIGO/Virgo era I will show our most recent predictions for direct detection of gravitational waves with the advanced LIGO/Virgo. I will target firsts detections and I will contrast them with new theoretical predictions. Several astrophysical implications are beginning to emerge.

• 10:00 – 10:30: A. Sesana [ slides ] ‹ The promise of multi-band gravitational wave astronomy ›
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  Alberto Sesana University of Birmingham The promise of multi-band gravitational wave astronomy I will discuss the implications of the recent LIGO discoveries for LISA. BHBs such GW150914 will be observable by LISA years before coalescence, making possible to see the same sources at different times in different GW bands. This has a number of interesting consequences and has the potential of enhance the scientific payouts of GW detections enormously.

• 10:30 – 11:00: Coffee Break
• 11:00 – 11:30: B. Sathyaprakash ‹ Exploring the Universe with third generation interferometers ›
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  Bangalore Sathyaprakash Penn State University and Cardiff University Exploring the Universe with third generation interferometers With two confirmed detections LIGO has firmly opened a new window to observe the Universe. These detections imply that binary black holes will dominate the population of sources we would observe but as detectors improve in strain sensitivity we expect to detect other merging stellar mass systems as also intermediate mass black holes, supernovae, and perhaps sources no one ever expected. In this talk I will discuss the immense science potential of future detectors and the scientific questions they will address.

• 11:30 – 12:00: S. Sato [ slides ] ‹ The status of DECIGO ›
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  Shuichi Sato Hosei University The status of DECIGO This talk will summarise the status of DECIGO and its precursor satellite Pre-DECIGO, mainly focusing on the recently re-planned roadmap to DECIGO. Very preliminary, but some basic ideas for conceptual design for these missions will be discussed.

• 12:00 – 12:30: G. Heinzel [ slides ] ‹ Satellite interferometry from LTP and GRACE Follow-On to LISA ›
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  Gerhard Heinzel AEI Hannover Satellite interferometry from LTP and GRACE Follow-On to LISA This talk will summarize the state of laser interferometry in space, from the now proven local interferometry on LISA Pathfinder to the soon to be launched long-distance interferometry on GRACE Follow-On and previous developments for LISA, and list what still is missing for LISA.

• 12:30 – 13:00: P. Binetruy [ slides ] ‹ Cosmology with LISA ›
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  Pierre Binetruy APC, Université Paris Diderot Cosmology with LISA I will review the scientific potential of the LISA mission from the point of view of the cosmology of the early Universe, emphasizing what we have learned in the last two years.

• 13:00 – 14:30: Lunch Break

Chairperson: S. Vitale

• 14:30 – 15:00: A. Giménez Cañete ‹ Beyond LISA Pathfinder ›
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  Alvaro Giménez Cañete ESA Beyond LISA Pathfinder

• 15:00 – 15:30: P. Hertz [ slides ] ‹ NASA Astrophysics Program: Present and Future ›
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  Paul Hertz NASA NASA Astrophysics Program: Present and Future

• 15:30 – 16:00: F. Safa [ slides ] ‹ ESA activities towards the Gravitation Waves Space Observatory ›
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  Frédéric Safa ESA ESA activities towards the Gravitation Waves Space Observatory

• 16:30 – 17:00: Coffee Break
• 17:00 – 17:30: H. Ward ‹ LPF Interferometry and route to LISA ›
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  Henry Ward University of Glasgow LPF Interferometry and route to LISA

• 17:30 – 17:50: J. Camp [ slides ] ‹ Development of a US Laser System for the Gravitational Wave Mission LISA ›
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  Jordan Camp NASA / GSFC Development of a US Laser System for the Gravitational Wave Mission LISA A highly stable and robust laser system is a key component of the space-based, Gravitational Wave mission LISA architecture. In this talk I will describe our plans to demonstrate a TRL 5 LISA laser system at Goddard Space Flight Center by 2017. The laser system includes a low-noise oscillator followed by a power amplifier. The oscillator is a low-mass, compact 10 mW External Cavity Laser, consisting of a semiconductor laser coupled to an optical cavity, built by the laser vendor Redfern Integrated Optics. The amplifier is a diode-pumped Yb fiber with 2.5 W output, built at Goddard. I will show noise and reliability data for the full laser system, and describe our plans to reach TRL 5 by 2017.

• 17:50 – 18:10: T. Schwarze [ slides ] ‹ Performance of an optical three-signal test for the LISA metrology ›
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  Thomas Schwarze AEI Hannover Performance of an optical three-signal test for the LISA metrology LISA will use high-precision heterodyne laser interferometry for the detection of gravitational waves at frequencies between 0.1 mHz and 1 Hz. A breadboard model for the electronic phase readout system (Phasemeter) of these interferometers was developed in the scope of an ESA technology development by a Danish German consortium and fullfills all performance requirements in electrical two-signal tests. Here we present the advances in the implementation of an optical testbed that enables tests of the whole LISA metrology, including prominently the Phasemeter and the photoreceivers. The experiment is based on an ultra-stable hexagonal optical bench. This allows the generation of three unequal heterodyne beatnotes that have a total phase sum of zero, thus providing the possibility to probe the readout for non-linearites in an optical three-signal test. This is critical for verifying the required readout precision in particular with a large dynamic range that LISA needs to implement time delay interferometry. A summary of the noise hunting conducted so far is given and the resulting performance close to the LISA requirement of 1 pm/sqrt(Hz) in the mHz regime is shown. Highlights include investigations into amplitude noise couplings and thermal effects in the experiment driven by power dissipation of the photoreceivers.

• 18:10 – 18:30: M. Laporte [ slides ] ‹ Status of the eLISA on table (LOT) electro-optical simulator for space based gravitational waves observatories ›
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  Matthieu Laporte APC, Université Paris Diderot - CNRS/IN2P3 Status of the eLISA on table (LOT) electro-optical simulator for space based gravitational waves observatories We intend to present the advancement and resullts of the eLISA on table experiment (LOT) which aims at characterizing the detection devices, validating the numerical models and studying the influence of the hardware on the detection algorithms. This hardware simulations is developed at APC Laboratory. The principle of the experiment is already validated. Noise reduction factor of $5.10^{7}$ for optical beat note and of $10^{9}$ for RF beat note has already been achieved. The ongoing work and results on the residual noise sources will be presented. It mostly consists in operating the simulator in a large vacuum chamber. Clock transfer noise can now also be simulated using electro-optical modulators recently added.

• 18:30 – 18:50: S. Apple ‹ UF Torsion Pendulum and GRS Technology Development ›
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  Stephen Apple University of Florida UF Torsion Pendulum and GRS Technology Development The University of Florida has developed a torsion pendulum facility to test and improve LISA gravitational reference sensor technology. This facility is largely based on the design of the four test mass torsion pendulum facility at the University of Trento. The UF torsion pendulum consists of a 1 m tungsten fiber that suspends a cross bar with mockups of the LISA test masses at each of the four ends, two of which are surrounded by electrode housings. This entire assembly is enclosed in a vacuum chamber. Recently, a number of improvements have been made to the UF torsion pendulum including the fabrication of a more flight-like GRS based on the LISA Pathfinder design, increased environmental monitoring and compensation, and the incorporation of a laser interferometer readout. This presentation will discuss the design of the UF torsion pendulum facility and the current acceleration noise performance.

• 18:50 – 19:10: J. Livas [ slides ] ‹ eLISA Telescope In-field Pointing and Scattered Light Study ›
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  Jeffrey Livas NASA Goddard Space Flight Center eLISA Telescope In-field Pointing and Scattered Light Study The orbital motion of the three spacecraft that make up the eLISA Observatory constellation causes long-arm line of sight variations of approximately +/- one degree over the course of a year. The baseline solution is to package the telescope, the optical bench, and the gravitational reference sensor (GRS) into an optical assembly at each end of the measurement arm, and then to articulate the assembly. An optical phase reference is exchanged between the moving optical benches with a single mode optical fiber (“backlink” fiber). An alternative solution, referred to as in-field pointing, embeds a steering mirror into the optical design, fixing the optical benches and eliminating the backlink fiber, but requiring the additional complication of a two-stage optical design for the telescope. We examine the impact of an in-field pointing design on the scattered light performance.

• 19:10 – 19:30: K. Isleif [ slides ] ‹ The LISA backlink – comparing optical phase reference systems ›
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  Katharina-Sophie Isleif AEI Hannover The LISA backlink – comparing optical phase reference systems The baseline LISA architecture uses telescope pointing to accommodate the breathing of the angle between two arms. Hence, the two optical benches within one LISA satellite need a flexible optical connection to exchange the phase information of the two local lasers. The optical path length difference of the exchanged light requires pm-level stability over up to 3° of tilt. The exchanged light is also used on each optical bench as local oscillator for the local interferometry. This makes the backlink one of the most critical and interesting subsystems of the LISA optical metrology with stringent requirements on the contamination of the light beams with undesired stray light. Here we report on the background, design and current status of an experiment that compares three key candidates for the LISA backlink that are collocated on two quasi-monolithic optical benches rotating relative to each other in a vacuum system. The candidates for the implementation, each one with a different stray light mitigation strategy, are a classic fiber backlink, a frequency shifted fiber backlink and a free beam backlink. Highlights include first results with a free beam backlink, including angular steering control, and the IfoCAD based design of the highly complex three backlink interferometer.

Wednesday 7th of September 2016

Chairperson: C. Sopuerta

• 09:00 – 09:30: T. Alexander ‹ EMRIs and the relativistic loss cone ›
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  Tal Alexander Weizmann Institute of Science EMRIs and the relativistic loss cone I briefly review advances in the understanding and modeling of relativistic stellar dynamics around massive black holes (MBHs) in galactic nuclei, following the inclusion of coherent relaxation and of secular processes in a new formal analytic description of the dynamics. I discuss implications for the rates and branching ratios of EMRIs and direct plunges.

• 09:30 – 10:00: R. Schoedel ‹ The stellar cusp around the Milky Way’s central black hole ›
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  Rainer Schoedel Instituto de Astrofísica de Andalucía (CSIC) The stellar cusp around the Milky Way’s central black hole The existence of stellar cusps in dense clusters around massive black holes is a fundamental, decades-old prediction of theoretical stellar dynamics. Yet, observational evidence has been difficult to obtain. With a new, improved analysis of high-angular resolution images of the central parsecs of the Galactic Center, we are finally able to provide the first solid evidence for the existence of a stellar cusp around the Milky Way's massive black hole. The existence of stellar cusps has a significant impact on predicted event rates of phenomena like tidal disruptions of stars and extreme mass ratio inspirals.

• 10:00 – 10:30: J. Gair ‹ Impact of eLISA design on EMRI Science ›
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  Jonathan Gair University of Edinburgh Impact of eLISA design on EMRI Science Extreme-mass-ratio inspirals are one of the key sources of gravitational waves for eLISA. Observations of these systems will provide information about the population of massive black holes in the LISA range in the local Universe. EMRI observations can be used as probes to estimate cosmological parameters. EMRI signals also provide exquisite tests of the predictions of general relativity and of the spacetime structure in the vicinity of astrophysical black holes. In this talk I will discuss how eLISA design choices impact the numbers and characteristics of the observed EMRI events and the corresponding impact on this exciting science.

• 10:30 – 11:00: Coffee Break
• 11:00 – 11:30: M. van de Meent [ slides ] ‹ Modelling spinning EMRIs with Self-Force ›
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  Maarten van de Meent University of Southampton Modelling spinning EMRIs with Self-Force (e)LISA science with EMRIs requires accurate templates which in turn require the orbital dynamics (self-force) to be modelled accurately up second order in the mass-ratio. I will present the current state-of-the-art on calculating the gravitational self-force on equatorial orbits in Kerr spacetime.

• 11:30 – 12:00: A. Gianninas [ slides ] ‹ A Progress Report on the Search for the Most Extreme Binary White Dwarfs ›
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  Alexandros Gianninas University of Oklahoma A Progress Report on the Search for the Most Extreme Binary White Dwarfs I will present the latest results from the ELM Survey, our ongoing search to discover extremely low-mass white dwarfs in compact binaries with periods less than a day. The shortest period systems are strong sources of gravitational waves and among the best verification sources for LISA.

• 12:00 – 12:30: I. Thorpe ‹ Initial Results from ST7-Disturbance Reduction System on LISA Pathfinder ›
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  Ira Thorpe NASA Initial Results from ST7-Disturbance Reduction System on LISA Pathfinder The European Space Agency LISA Pathfinder spacecraft was launched on December, 2, 2015 carrying the NASA contribution ST7-Disturbance Reduction System (ST7-DRS). The objective of ST7-DRS is to demonstrate drag-free control and noise reduction technologies for future missions, especially a future space-based gravitational wave observatory. The system consists of a pair of Colloid Micro-Newton Thruster clusters and a computer with control algorithms. Data from the host platform is used for inertial and attitude sensing. ST7-DRS was initially powered on in January 2016 for an on-orbit check out and was fully commissioned in late June and early July. This presentation will report preliminary results relative to the 0.1 micro-Newton/ rt Hertz thrust noise requirement and the 10 nanometer/rt Hertz position control requirement.

• 12:30 – 13:00: G. Jin [ slides ] ‹ Ongoing development of detection of gravitational waves in space in China ›
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  Gang Jin Institute of Mechanics, Chinese Academy of Sciences Ongoing development of detection of gravitational waves in space in China In this talk, we will present the ongoing development of gravitational wave detection in space in China. We will describe the preliminary mission design, primary science drivers, program for technological developments and the roadmap.

• 13:00 – 14:00: Lunch Break
• 15:10 – 15:30: Coffee Break

Thursday 8th of September 2016

Chairperson: P. Binetruy

• 09:00 – 09:30: R. Blandford ‹ The Future of Black Hole Astrophysics in the LISA-VIRGO-LPF Era ›
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  Roger Blandford Stanford University The Future of Black Hole Astrophysics in the LISA-VIRGO-LPF Era

• 09:30 – 09:50: C. Moore [ slides ] ‹ Observing black hole merger kicks directly with gravitational waves ›
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  Christopher Moore University of Cambridge, UK Observing black hole merger kicks directly with gravitational waves Black hole binaries in the final moments before merger radiate gravitational waves anisotropically imparting a recoil, or kick, velocity to the merger remnant. If a component of the kick is directed along the line-of-sight the observed gravitational radiation from the merger and ringdown will be gradually Doppler shifted as the kick velocity accumulates. I will present the results of recent work on accurately modelling the kick, as well as a simple prescription for including the effects of the kick in existing gravitational waveform models. These models may then be used to assess prospects for detecting and measuring black hole kicks with a variety of different detectors. We find that the eLISA mission is particularly well suited to observing black hole kicks; it will be capable of measuring supermassive black hole kick velocities as low as $\sim500\mathrm{km}\,\mathrm{s}^{-1}$ which are expected to be ubiquitous.

• 09:50 – 10:10: N. Tamanini [ slides ] ‹ Late time cosmology with eLISA ›
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  Nicola Tamanini IPhT - CEA/Saclay Late time cosmology with eLISA In this talk I will consider the application of eLISA as a probe of the late- time cosmological expansion. In particular I will first review the concept of standard sirens and how these can be used to investigate the distant-to-redshift relation. I will then discuss the best strategies to obtain as many standard sirens as possible, taking into account what kinds of electro-magnetic counterparts could reasonably be detected and by which instruments. Finally, employing realistically simulated data, I will present the eLISA forecasted constraints on the cosmological parameters of LambdaCDM and alternative dark energy models.

• 10:10 – 10:30: I. Dvorkin [ slides ] ‹ A synthetic model of the gravitational wave background from evolving binary compact objects ›
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  Irina Dvorkin Institut d'Astrophysique de Paris A synthetic model of the gravitational wave background from evolving binary compact objects Modeling the stochastic gravitational wave background is a key objective in the era of gravitational wave astronomy. In this talk I will present a model framework that follows the evolution of single and binary compact objects in an astrophysical context. This framework describes the formation and merger rates of binaries, the evolution of their orbital parameters with time and is embedded in a galaxy evolution model. This modular approach allows to test and constrain different ingredients of the model, including stellar evolution, metallicity of the interstellar medium, black hole formation scenarios and properties of binary systems. This framework is applied in the context of an astrophysical setup which matches the observed metallicity of the interstellar medium and optical depth to reionization to calculate the black hole mass distribution and the gravitational wave background produced by inspiraling and merging black holes. I will focus on the contribution from inspiraling stellar-mass binary black holes that have not merged during the Hubble time which produce a characteristic signal that can help constrain the properties of binary black holes. Finally, I will discuss possible applications in the context of other gravitational wave sources, such as super-massive black holes.

• 10:30 – 11:00: Coffee Break
• 11:00 – 11:30: A. Petiteau [ slides ] ‹ LISA science performance in the context of LISAPathfinder first results and simulation for LISA ›
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  Antoine Petiteau APC - Université Paris-Diderot LISA science performance in the context of LISAPathfinder first results and simulation for LISA The LISAPathfinder first results give the most realistic estimation of the acceleration noise of LISA. This is a key component for estimating the scientific potential of the future LISA mission. The presentation will show the preliminary results of the ongoing study coupling the LISAPathfinder first results with LISA simulations. An overview of the scientific potential for the various sources will be given for few LISA configurations. We will show that using the LISAPathfinder first results most part of the LISA scientific goals are already reached which is expected given the excellence of these results. The ongoing developments for introducing the LISAPathfinder results, the new LISA technologies and gravitational waveforms in the LISA simulations will also be briefly introduced through a presentation of the activities of the LISA working group which is developing the end-to-end simulator of the mission.

• 11:30 – 12:00: N. Cornish [ slides ] ‹ Fast, fully precessing frequency domain waveforms for analyzing black hole mergers with LISA ›
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  Neil Cornish Montana State University Fast, fully precessing frequency domain waveforms for analyzing black hole mergers with LISA Until now, the simulation and analysis of LISA observations of fully spin precessing black hole mergers required expensive time domain calculations. I will describe the construction of new, closed form, frequency domain waveforms, including the full instrument response, that dramatically speed up the study of LISA black hole mergers.

• 12:00 – 12:30: A. Klein [ slides ] ‹ Supermassive Black Hole Observations with eLISA ›
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  Antoine Klein Institut d'Astrophysique de Paris Supermassive Black Hole Observations with eLISA We compare the science capabilities of different eLISA configurations for supermassive black hole binary observations. We vary the numer of links, armlength, low-frequency noise level, and mission duration. We consider different binary formation scenarios, with different black hole seeding mechanisms, and including delays between galaxy mergers and black hole mergers.

• 12:30 – 13:00: S. Hughes [ slides ] ‹ Measuring EMRIs: A reality check ›
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  Scott Hughes Massachusetts Institute of Technology Measuring EMRIs: A reality check Inspirals of stellar mass compact bodies into massive black holes --- extreme mass ratio inspirals, or EMRIs -- have long been regarded as one of the most important source categories for a LISA-type mission. EMRI GWs are exquisitely sensitive to properties of the larger black hole's spacetime, and promise enable precise measurements of black hole properties, including strong-field gravity tests. These waves are difficult to measure, with the signal's power smeared out over $\sim 10^5 - 10^6$ radians of orbital phase. Successful EMRI measurement will require matching signals with templates that faithfully match phase over these many radians. In this talk, I will argue that we need to revisit EMRI data analysis to accurately assess how ready we are to measure these sources. It will be important to make EMRI models that accurately incorporate the unique features that make their waves so interesting and hard to measure, and to assess the challenge of measuring these waves in realistic data.

• 13:00 – 14:30: Lunch Break

Chairperson: Ch. Caprini

• 14:30 – 15:00: L. Mayer [ slides ] ‹ Massive black hole mergers and their timescales: connecting galaxy formation with gravitational wave science ›
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  Lucio Mayer CTAC, Institute for Computational Science, University of Zurich Massive black hole mergers and their timescales: connecting galaxy formation with gravitational wave science I will present results of recent simulations that, for the first time, can follow the orbital decay of a pair of supermassive black holes from cosmological distances to the gravitational wave driven phase, using cosmological galaxy formation simulations mapped to a state-of-the-art GPU-based N-Body code with post-newtonian corrections. We show that the SMBH merger timescale is strongly redshift dependent, being orders of magnitude smaller than the Hubble time at z > 2, but becoming a significant fraction of the Hubble time at low redshift. The remarkable difference is due to the large difference in the galaxy host potential at high and low redshift. Likewise, we discuss results of other simulations focusing on very gas-rich environments in which MBHs are embedded in a cold circumnuclear disks, showing how stochastic torques can arise in cold clumpy disks. These torques generally slow down orbital decay by 1-2 orders of magnitude even at high redshift. These simulations provide the initial steps towards a real understanding of the MBH merger timescales, a crucial aspect for forecasts of gravitational wave event rates in the eLISA detection window as well as being of interest for detections with Pulsar Timing Arrays.

• 15:00 – 15:30: S. Babak ‹ Enchilada: analysis of simulated eLISA data set ›
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  Stanislav Babak Albert Einstein Institut Enchilada: analysis of simulated eLISA data set I will present a new pipeline for generating simulated eLISA data set based on the astrophysical populations and review currently available analysis methods.

• 15:30 – 16:00: A. Ricciardone [ slides ] ‹ Primordial Gravitational Waves and eLISA ›
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  Angelo Ricciardone University of Stavanger Primordial Gravitational Waves and eLISA 100 years ago, Einstein predicted the existence of Gravitational Waves (GW) as a consequence of his theory of General Relativity. Today we have confirmed the Einstein predictions with the recent detection of GW150914 and GW151226 by the advanced LIGO (aLIGO) detector. This ground based detector will be joined in the next years by the space detectors “eLISA”, that will survey the low-frequency gravitational-wave sky (from 0.1 mHz to 1 Hz), a frequency band inaccessible from the Earth. The eLISA interferometer, in addiction to detection and characterization of GW of astrophysical origin (such that coming from coalescences of massive black holes and from the inspirals of stellar-mass black holes), as we will see, it will also give strong information about other possible sources of GW in the early universe, like particle production during inflation, phase transitions, etc. In this talk I will briefly review the physics of primordial gravitational waves and then I will mainly discuss on the promise of these measurements for giving informations about the physics of the early universe.

• 16:00 – 16:30: S. Sanidas [ slides ] ‹ Can eLISA save the day? Hunting for cosmic strings in the SKA era. ›
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  Sotiris Sanidas API, University of Amsterdam Can eLISA save the day? Hunting for cosmic strings in the SKA era. Cosmic strings are 1-D topological defects which may have formed in the early Universe, and continue to exist and evolve till the present time. Being, literally, relics of a more symmetric phase of the Universe, the detection of cosmic strings will provide us an extremely high energy cosmic lab, at energies unachievable in human-made accelerators. Although cosmic strings are related with a plethora of observational signatures, gravitational waves (GWs) are one of the main ones used to detect them. So far, Pulsar Timing Arrays (PTAs) have been used to set the most stringent constraints on the cosmic string tension (their energy scale) and are considered to be the GW detector type that has most chances in detecting their GW signal. PTA limits on the stochastic gravitational wave background (SGWB) are continuously improving as more and more high precision data are collected, and they will get a significant boost with the SKA in the near future. If PTAs detect a cosmic string SGWB, then eLISA will probably do so as well. However, if SKA fails to make a detection of a cosmic strings' SGWB, will eLISA have any chance to achieve such a goal? The answer to this question will be the main topic of this talk, along with the expected capabilities of some characteristic eLISA designs.

• 16:30 – 17:00: Coffee Break
• 17:00 – 17:30: G. Servant [ slides ] ‹ Probing cosmological phase transitions with eLISA ›
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  Geraldine Servant DESY and U. Hamburg Probing cosmological phase transitions with eLISA We investigate the potential for eLISA to detect the stochastic gravitational wave background produced by strong first-order cosmological phase transitions. We discuss the resulting contributions from bubble collisions, magnetohydrodynamic turbulence, and sound waves to the stochastic background, and estimate the total corresponding signal predicted in gravitational waves. The projected sensitivity of eLISA to cosmological phase transitions is computed in a model-independent way for various detector designs and configurations. By applying these results to several specific models, we demonstrate that eLISA is able to probe many well-motivated scenarios beyond the Standard Model of particle physics predicting strong first-order cosmological phase transitions in the early Universe.

• 17:30 – 17:50: D. Weir [ slides ] ‹ Acoustic waves and the detectability of first-order phase transitions by eLISA ›
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  David Weir University of Helsinki Acoustic waves and the detectability of first-order phase transitions by eLISA In various extensions of the Standard Model it is possible that the electroweak phase transition was first order. This would have been a violent process, involving the formation of bubbles and associated shock waves. Not only would the collision of these bubbles and shock waves be a detectable source of gravitational waves, but persistent acoustic waves could enhance the signal and improve prospects of detection by eLISA. I will summarise the results of a recent campaign to model such a phase transition based on large-scale hydrodynamical simulations, and its implications for the eLISA mission.

• 17:50 – 18:10: M. Bonetti [ slides ] ‹ Post-Newtonian Dynamics of Massive Black Holes Triplets ›
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  Matteo Bonetti Insubria University Post-Newtonian Dynamics of Massive Black Holes Triplets Massive black-hole binaries (MBHBs) are thought to be the main source of gravitational waves (GWs) in the low-frequency domain surveyed by ongoing and forthcoming Pulsar Timing Array campaigns and future space-borne missions, such as eLISA. However, many low-redshift MBHBs in realistic astrophysical environments may not reach separations small enough to allow significant GW emission. This “last-parsec problem” can be eased by the appearance of a third massive black hole (MBH) – the “intruder” – whose action can force, under certain conditions, the inner MBHB on a very eccentric orbit, hence allowing intense GW emission eventually leading to coalescence. A detailed assessment of the process, ultimately driven by the induced Kozai-Lidov oscillations, requires a general relativistic treatment and the inclusion of environmental effects, such as the galactic potential and the hardening caused by scattering off background stars. In order to tackle this problem, we developed a three-body Post-Newtonian (PN) code framed in a realistic galactic potential, including both non-dissipative 1PN and 2PN terms, and dissipative terms such as 2.5PN effects, orbital hardening of the outer binary, and the effect of the dynamical friction.

• 18:10 – 18:30: J. Garcia-Bellido [ slides ] ‹ Gravitational waves from primordial black holes as dark matter ›
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  Juan Garcia-Bellido Universidad Autonoma Madrid Gravitational waves from primordial black holes as dark matter 20 years ago, we predicted that primordial black holes would form via the gravitational collapse of matter associated with peaks in the spectrum of fluctuations, and that they could constitute all of the dark matter today. More recently, we predicted the mass distribution of PBH, which peaks at 50 Msun and whose tails could be responsible for the seeds of galaxies. LIGO has recently detected gravitational waves from the inspiraling of two 30 Msun black holes. In arXiv:1603.05234, we propose that LIGO has actually detected dark matter in the form of PBH, and predict that within 10 years, an array of GW detectors (i.e. LIGO, VIRGO, KAGRA, INDIGO, etc.) could be used to determine the mass distribution of PBH dark matter with 10% accuracy.

• 18:30 – 18:50: T. Regimbau [ slides ] ‹ Searching for the stochastic gravitational-wave background with Advanced LIGO and Advanced Virgo ›
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  Tania Regimbau CNRS/ARTEMIS Searching for the stochastic gravitational-wave background with Advanced LIGO and Advanced Virgo In the coming years observations by Advanced LIGO and Advanced Virgo may allow for a detection of a stochastic background of gravitational waves. Sources for the stochastic gravitational wave background could be cosmologically or astrophysically produced. The implications of the recent observations of GW150914 and GW151226 indicate that a stochastic background produced from the superposition of binary black hole mergers throughout the history of the universe may be detectable by LIGO and Virgo in the coming years. Presented will be a summary of the current LIGO-Virgo search for such a stochastic background using data from the first observing run, and what implications those results will have on different models.The projected sensitivities of future observation runs with Advanced LIGO and Advanced Virgo will also be given. Finally, information on how the stochastic background searches by ground-based detectors and LISA can complement one another will be presented.

• 18:50 – 19:10: M. Pieroni [ slides ] ‹ Primordial GW from universality classes of pseudo-scalar inflation ›
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  Mauro Pieroni Laboratorie APC Primordial GW from universality classes of pseudo-scalar inflation I discuss the possibility of generating an observable gravitational wave (GW) background by coupling a pseudo-scalar inflaton to some abelian gauge fields. The analysis is performed by dividing inflationary models into universality classes. One of the most promising scenarios is Starobinsky inflation, which may lead to the generation of observational signatures both in upcoming CMB detectors as well as for direct GW detectors. In particular the predicted signal would both be observable in ground-based detectors, such as advanced LIGO, and in space-based detectors, such as LISA. The complementarity between the CMB and direct GW detection may be used to extract informations on the microphysics of inflation. The mechanism discussed in this talk may also be relevant for the generation of heavy primordial black holes (PBH).

Friday 9th of September 2016

Chairperson: G. Mueller

• 09:00 – 09:30: K. Holley-Bockelmann [ slides ] ‹ The Known Unknowns: predicting the landscape of LISA black hole sources ›
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  Kelly Holley-Bockelmann Vanderbilt University, Nashville TN The Known Unknowns: predicting the landscape of LISA black hole sources

• 09:30 – 10:00: E. Rossi ‹ Supermassive black hole seeds: updates on the quasi star model ›
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  Elena Maria Rossi Leiden Observatory, LeidenUniversity Supermassive black hole seeds: updates on the quasi star model This year, we published two papers investigating further physical effects related to formation of supermassive black hole seeds from direct collapse of gas, at the centre of porto-galaxies. I'd like to report on our findings and draw consequences for seeds detections.

• 10:00 – 10:30: C. Mingarelli [ slides ] ‹ The Gravitational-Wave Universe seen by Pulsar Timing Arrays ›
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  Chiara M. F. Mingarelli Max Planck Institute for Radio Astronomy The Gravitational-Wave Universe seen by Pulsar Timing Arrays Galaxy mergers are a standard aspect of galaxy formation and evolution, and most (likely all) large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes should in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz and microhertz regime. Processes in the early Universe such as relic gravitational waves and cosmic strings may also generate gravitational radiation in the same frequency band. An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in the nanohertz band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent limits which have emerged from international efforts to constrain astrophysical phenomena at the heart of supermassive black hole mergers.

• 10:30 – 11:00: Coffee Break
• 11:00 – 11:30: S. Smartt ‹ Searching for the electromagnetic counterparts to gravitational wave sources ›
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  Stephen Smartt Queen's University Belfast Searching for the electromagnetic counterparts to gravitational wave sources With the discovery of gravitational waves from compact binaries, the next challenge for the traditional astronomical community is to search for electromagnetic counterparts. While binary black hole mergers in a vacuum have not been predicated to be bright at any wavelengths, some mechanisms have been proposed that may lead to high energy and optical/NIR afterglows. There are more firm predictions for merging binaries involving neutron stars. I will review the efforts to date to search for the counterparts to the first two discoveries - GW150914 and GW151226. The community’s efforts illustrate the capability and sensitivities that are possible. With a particular emphasis on Pan-STARRS and PESSTO, I will show that binary neutron star mergers within about 100Mpc are detectable and that searchers for unexpected and unusual signatures are worthwhile endeavours.

• 11:30 – 12:00: J. Bergé ‹ MICROSCOPE: the first few months in orbit ›
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  Joel Bergé ONERA MICROSCOPE: the first few months in orbit MICROSCOPE is a CNES/ONERA mission that aims to test the Weak Equivalence Principle in space with an unprecedented accuracy. It was launch on April 25, 2016. We will present the science objectives and the technology of the mission, and report on the first few months of operation.

• 12:00 – 12:30: O. Jennrich ‹ The preparation for L3 – building on LISA Pathfinder ›
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  Oliver Jennrich ESA The preparation for L3 – building on LISA Pathfinder The successful development and operation of LISA Pathfinder mission has paved the way for a future gravitational wave mission that will inherit many of the technologies demonstrated in LISA Pathfinder. For the remaining technologies, dedicated technology development activities are ongoing or will be started in the very near future. The presentation will give an overview about the status of the technology and the development activities, the plans for future developments and the experience that can be gained from operating LISA Pathfinder for the L3 mission, in particular for the commissioning and the data-analysis.

• 13:00 – 14:30: Lunch Break

List of Posters, Slides and Recordings

A) LISA Pathfinder - Results

• Armano Michele
  ‹ Demonstrating the LPF Science Archive ›
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  Michele Armano ESA/ESAC Demonstrating the LPF Science Archive We will informally sit with our laptop and show the work in progress on the LPF Science Archive, the ESA portal granting access to LPF data to the whole scientific community. We shall walk any interested observer though the main features of the page, show how to query and download data, collecting early remarks to improve the product ahead of its first release.

• Audley Heather E.
  ‹ LISA Pathfinder: OMS monitoring during operations ›
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  Heather E. Audley AEI, Hannover LISA Pathfinder: OMS monitoring during operations The LISA Pathfinder mission has demonstrated excellent performance. In addition to having achieved the main mission goals, data has been collected from the various subsystems throughout the duration of the mission. This data is a valuable resource, both for a more complete understanding of the LPF satellite and the differential acceleration measurements, and for the design of a future LISA mission. Initial analysis of the Optical Metrology System data was performed as part of daily system monitoring, and more in-depth analyses are ongoing. This contribution presents results from these analyses.

• Born Michael
  ‹ OPD loop characterisation ›
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  Michael Born AEI Hannover OPD loop characterisation The high precision test mass position measurement on LISA Pathfinder is made via heterodyne interferometry. Two laser beams with slightly offset frequencies are superimposed, and their beat signal measured. Disturbances in the fibres of the two beams induce optical pathlength differences (OPD), which spoil the measurement. A control loop is used to correct these pathlength differences. In this talk an overview of the OPD control loop and its performance on-ground and in-flight will be presented.

• Dunn Charles
  ‹ Initial Results from ST7-Disturbance Reduction System on LISA Pathfinder ›
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  Charles Dunn Jet Propulsion Laboratory, California Institute of Technology Initial Results from ST7-Disturbance Reduction System on LISA Pathfinder The European Space Agency LISA Pathfinder spacecraft was launched on December, 2, 2015 carrying the NASA contribution ST7-Disturbance Reduction System (ST7-DRS). The objective of ST7-DRS is to demonstrate drag-free control and noise reduction technologies for future missions, especially a future space-based gravitational wave observatory. The system consists of a pair of Colloid Micro-Newton Thruster clusters and a computer with control algorithms. Data from the host platform is used for inertial and attitude sensing. ST7-DRS was initially powered on in January 2016 for an on-orbit check out and was fully commissioned in late June and early July. This presentation will report preliminary results relative to the 0.1 micro-Newton/ rt Hertz thrust noise requirement and the 10 nanometer/rt Hertz position control requirement.

• Ferroni Valerio
  ‹ Constraints on LISA Pathfinder’s self-gravity: design requirements, estimates and testing procedures ›
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  Valerio Ferroni university of trento Constraints on LISA Pathfinder’s self-gravity: design requirements, estimates and testing procedures LISA Pathfinder was successfully launched on 3rd December 2015 aiming to put a pair of test masses in free fall with a residual acceleration noise non exceeding 3x10-14ms-2Hz-1/2. The spacecraft is responsible of the local gravitational field which will interact with the two proof test-masses. Potentially, such a force interaction might prevent to achieve the targeted free-fall level originating a significant source of noise. We balanced this gravitational force with sub-nano-ms-2 accuracy, guided by a protocol based on measurements of the position and the mass of all parts that constitute the satellite, via finite element calculation tool estimates. In this talk we will introduce requirements, design and foreseen on-orbit testing procedures.

• Gibert Ferran
  ‹ Thermal experiments on LISA Pathfinder's Inertial Sensors ›
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  Ferran Gibert Università di Trento / INFN Thermal experiments on LISA Pathfinder's Inertial Sensors The Inertial Sensors onboard LISA Pathfinder are sensitive to temperature fluctuations around the Test Masses. Indeed, temperature gradients induce forces on the masses through different thermal effects: radiometer effect, radiation pressure and asymmetric outgassing. In this talk/poster we review the thermal experiments carried out during the flight to characterise these effects and to assess their contribution to the LTP acceleration sensitivity.

• Grimani Catia
  ‹ Galactic cosmic-ray short-term variations aboard LISA Pathfinder ›
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  Catia Grimani University of Urbino "Carlo Bo" - INFN Florence Galactic cosmic-ray short-term variations aboard LISA Pathfinder The LISA Pathfinder (LPF) spacecraft was launched on December 3rd 2015 and since January 20th 2016 is orbiting about the L1 Lagrangian point. After the mission launch the interplanetary medium went through a long period during which no major solar energetic particle (SEP) events were observed aboard LPF. This occurrence allowed us to study galactic cosmic-ray (GCR) short-term variations on the basis of the observed LPF radiation monitor particle count rate as a function of time. This is one of the most controversial subjects in cosmic-ray physics. The LPF data were compared to those of several neutron monitors on Earth. Polar neutron monitors were found the most proper for comparison due to the low threshold of the LISA-PF particle energy measurements. In order to correlate the LISA-PF observations to the Earth neutron monitor measurements, the position of the satellite with respect to the ecliptic was taken into account. Effects of corotating and transient solar wind structures possibly inducing GCR short-term variations were studied. The effects of GCR short-term variations on the test-mass charging are expected to be of the order of a few per cent, however their actual role remains to be fully understood. It would be more than important, before mission end, to evaluate the effects of a strong SEP event on LPF to be compared to Monte Carlo simulations.

• Inchauspe Henri
  ‹ LISA Pathfinder DFACS performances and study of the degrees of freedom besides the sensitive axis ›
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  Henri Inchauspe Laboratoire APC - CNRS/Université Paris Diderot LISA Pathfinder DFACS performances and study of the degrees of freedom besides the sensitive axis A study devoted to assess the control performances of every dynamical degree of freedom in LISA Pathfinder closed loop system, i.e. the angular and the linear displacement of the spacecraft and the test masses. The effect of sensing and actuation noise on the output sensing channel will be studied and measured transfer functions of the closed loop, in particular other than the one concerning the sensitive axis, will be presented and compared to the state space model developed by the collaboration. We will show that this study can help to track down the various sources of noise at the origin of the residual differential acceleration between the test masses. As examples, we will discuss in particular two cases where the loop properties plays a role in the final performances we get in term of residual differential acceleration: the low frequency part of the measurement frequency band, typically below 1 mHz, where inertia forces driven by the star tracker noise contributes to the noise budget, and a higher frequency band, between 20 mHz and 200 mHz, where the lack of authority of the Drag-Free loop allows for some coupling between the spacecraft and the observed test masses motions.

• Karnesis Nikolaos
  ‹ System identification experiments on-board the LISA Pathfinder ›
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  Nikolaos Karnesis AEI Hannover System identification experiments on-board the LISA Pathfinder The LISA Pathfinder (LPF) mission is testing key technologies for future Gravitational-Wave observatories, by monitoring two test masses in a near-perfect gravitational free-fall conditions. The LPF mission exceeded all expectations by measuring differential acceleration between the two test-masses at the level of $5.2\pm0.1$ fm s$^{-2}/\sqrt{\mbox{Hz}}$ for frequencies of $0.7$ to $20$ mHz. In order to make this measurement of the differential acceleration, it is necessary to estimate the key dynamical parameters of the system. For that reason, several system identification experiments were performed throughout the duration of the mission. These experiments can be divided into two categories; the x-axis and the cross-talk investigations. The first case refers to the dynamics along the sensitive longitudinal interferometer measurement, while the second to the various cross-couplings contributing to the same measurement. In this talk we shall discuss the design of aforementioned experiments as well as the strategies followed for their analysis. Finally we will summarise the main parameter estimation results during the nominal mission operations.

• Korsakova Natalia
  ‹ Radiation pressure and Test Mass reflectivity in LPF ›
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  Natalia Korsakova AEI Hannover Radiation pressure and Test Mass reflectivity in LPF (accepted) Radiation pressure and Test Mass reflectivity during the LPF nominal operations. Optical metrology system is the instrument that delivers the main scientific measurement for LISA Pathfinder, the precise measurement of the distance between two probe bodies following geodesics. The measurement is performed by the interferometer that recombines two beams one that is reflected from the free falling test masses and the other that is not. The series of experiments that will be described here focus on the modulation of the beam powers that among others allow us to measure the test mass reflectivities and calculate force acting on the test masses from the radiation pressure. These measurements give way to calibrate the photodiodes and perform a long term monitoring of their efficiencies which is an important aspect for the future planning and design of the LISA optical metrology system. In addition we can estimate the contribution of the radiation pressure noise to the overall noise budget.

• López Zaragoza Juan Pedro [ pdf ]
  ‹ Magnetic environment on-board LISA Pathfinder ›
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  Juan Pedro López Zaragoza Institut de Ciències de l'Espai (CSIC-IEEC) Magnetic environment on-board LISA Pathfinder The magnetic field on-board LISA Pathfinder plays an important role in the understanding the LPF noise budget. Fluctuations of the field and the field gradient in the test mass position will directly translate into a force exerted on the test mass and therefore the magnetic field needs to be correctly characterised. This turns out to be a complex problem since there are more than 100 electronic devices inside the spacecraft contributing to the overall magnetic field and the only available information is the read-out from 4 tri-axial fluxgate magnetometers. Besides, in order to asses the force noise contribution to the differential force measurement, we are interested in the magnetic field in the position of the TM's. Since the magnetometers are relatively far from them an extrapolation is needed. In this talk we introduce the method followed to characterize the LPF environmental magnetic field using in-flight data and the extrapolation of these measurement to asses the magnetic field in the TMs position.

• Martín Víctor [ pdf ]
  ‹ Development platform for LPF payload flying software ›
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  Víctor Martín Institut de Ciències de l'Espai (CSIC-IEEC) Development platform for LPF payload flying software LISA Pathfinder (LPF) has placed two test masses in a nearly perfect gravitational free-fall, and has controlled and measured their relative motion with unprecedented accuracy. To control the Lisa Technology package (LTP) an embedded payload control software has been developed to be executed inside the Data Management Unit (DMU). To produce it, a huge infrastructure has been built during more than 10 years. This Poster will summarize and describe the infrastructure that allow us to develop, validate with fast and repeatable tests, and execute ours BSW and ASW in pure 100% software emulated/simulated hardware environment, and/or in real hardware emulating all LTP subsystems or OBC when needed.

• Meshksar Neda
  ‹ GRS vs. OMS Calibration ›
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  Neda Meshksar Institute for Geophysics, ETH Zurich GRS vs. OMS Calibration Test mass (TM) movement on board LISA Pathfinder spacecraft (S/C) is sensed according to the optical and electrostatic readout methods. Based on optical readout method the optical metrology system (OMS) measures the displacement of the drag-free TM relative to the S/C and also relative to the other TM, along the main measurement axis, labeled x. It also measures the rotation of both test masses around y and z. On the other hand, the gravitational reference sensor (GRS) provides the electrostatic readout of the displacement and rotation along all degrees of freedom for both test masses. We have monitored the data resulted from system identification experiments during the LPF science operation (March – June 2016) and we present the calibration of GRS measurements with respect to OMS for displacements along x-axis. The relative gain and relative offset have been obtained by a linear fit of GRS vs. OMS readout. We have excluded any straightforward correlation with temperature and non-linearity in the GRS electronics. We observed that the relative calibration gain does not obey a clear trend. The origin of such oscillation is still under investigation.

• Plagnol Eric
  ‹ LISAPathfinder: Studying the quasi-continuous behavior of DeltaG ›
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  Eric Plagnol CNRS LISAPathfinder: Studying the quasi-continuous behavior of DeltaG The quasi-continuous behavior of DeltaG, during the LISA Pathfinder mission, presents an intriguing behavior with some very low frequency trends. Part of this has been explained by the propellant consumption. This talk will present various hypothesis that can be made to explain the remaining features.

• Rivas Francisco [ pdf ]
  ‹ Themo-elastic induced noise in LISA Pathfinder ›
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  Francisco Rivas Institut de Ciències de l'Espai (CSIC-IEEC) Themo-elastic induced noise in LISA Pathfinder Themal gradients on board the LISA Pathfinder mission can induce effects with a potential impact to perturb the main differential acceleration measurement between both free-falling test masses. Apart from thermal forces arising due to gradients around the test mass, thermo-elastic effects can also contribute to the instrument noise. There are two locations where such a distortion can be critical. First, the optical window, i.e. the interface between the optical bench and the test mass. This optical element –-the only not bonded on the Zerodur optical bench--- is clamped in a Titanium ring and therefore is susceptible to mechanical stress or changes in the refractive index due to thermal gradients across the glass. The second location are the struts holding the optical bench inside the thermal shield acting as the main thermal link to the outside (thermally noisier) environment. Temperature changes in these structures can induce net displacements or tilts of the bench with direct impact on the interferometer read-out. Both temperature sensors and heaters were located in these locations as part of the thermal diagnostics subsystems and experiments have been performed during operations. Here we report on the results of these experiments and first estimates on the contribution to the mission noise budget coming from thermo-elastic distortions.

• Robertson David
  ‹ LPF Interferometery – what can the beam position variations tell us ›
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  David Robertson University of Glasgow LPF Interferometery – what can the beam position variations tell us In LPF the interferometer is read out by 8 quadrant photodiodes, each with two beams on it to produce the heterodyne signal. These beams all probe different parts of the optical system. Their positions on the diodes can be affected by a number of things such as mechanical distortions of the OBI, beam pointing variations from the FIOS, both of which may be thermally driven, and long term drifts of the mechanical system. We present the measurements of these beam positions over the course of the LPF nominal mission and draw some conclusions about the thermal sensitivity and structural stability of the OBI system.

• Russano Giuliana [ pdf ]
  ‹ LISA Pathfinder Free-fall Mode: data analysis approaches for measuring sub-femto-g differential acceleration in presence of gaps in the data ›
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  Giuliana Russano University of Trento - TIFPA LISA Pathfinder Free-fall Mode: data analysis approaches for measuring sub-femto-g differential acceleration in presence of gaps in the data The LISA Pathfinder geodesic explorer mission for gravitational wave astronomy has demonstrated a residual acceleration between two free falling test masses at sub-femto-m/s^2Hz^1/2 level at frequency down to 0.1 mHz. The actuation force applied to compensate the presence of a large and constant relative acceleration between these two objects, necessary to hold them centered inside the orbiting apparatus, introduces a source of force noise at frequency near and below the mHz. The ‘free-fall mode’ actuation control scheme has been designed to suppress this noise source, limiting the actuation to brief periodic impulses, with test masses in free fall in between two “kicks”. This actuation-free motion is then analysed for the remaining sources of acceleration ultra noise. We show in detail the main data analysis techniques developed in order to deal with the presence of short gaps in the data, produced by removing the periodic actuation applied during kicks. These are the windowing technique, based on masking the gaps with spectral windows; the gap-patching technique, consisting in filling gaps with artificial data; BH-filtering approach, a filtering technique to reduce spectral leakage from high frequencies.

• Schleicher Alexander
  ‹ LISA Pathfinder - LTP & DFACS Lessons Learned During Commissioning ›
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  Alexander Schleicher Airbus DS LISA Pathfinder - LTP & DFACS Lessons Learned During Commissioning With the successful launch and commissioning of LISA Pathfinder begins the journey towards LISA and the important task of considering the valuable lessons that have been learned during the commissioning of the SC and the instrument and the implications for LISA. This paper focuses primarily on the instrument and drag free control aspects of the mission and thus focuses on the period from TM decaging up to the successful verification of the science mode performance. In addition, also the successful verification of the charge management system is considered. Within this context the paper focuses on the important lessons to be derived from the commissioning results and extends those lessons towards LISA. The main topics covered here are the robustness of the TM release and capture, the robustness of the mode transitions from the non drag free modes into the high performance drag free modes as well as onboard charge estimation and control.

• Slutsky Jacob
  ‹ LISA Pathfinder as a drag-free accelerometry instrument ›
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  Jacob Slutsky Univ of Maryland-Baltimore County LISA Pathfinder as a drag-free accelerometry instrument The LISA Pathfinder mission includes the two highest precision drag free accelerometers ever flown. While the baseline scientific purpose of the mission uses the residual of the differential acceleration between them to validate sensitivity towards a LISA mission, each individual sensor provides an unparalleled measure of the full six-dimensional spacecraft motion to which the mission was designed to be insensitive. We will discuss the commonalities between this approach and the conventional one-dimensional differential acceleration measurement, as well as challenges and methods unique to this analysis. Further, we will discuss the varied applications of this analysis, including characterization of thruster noise and performance, as well as micrometeoroid detection.

• Thorpe Ira
  ‹ LISA Pathfinder as a Micrometeoroid Instrument ›
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  Ira Thorpe NASA/GSFC LISA Pathfinder as a Micrometeoroid Instrument LISA Pathfinder is perhaps the most precise accelerometry instrument ever flown in space. The drag-free control system can sense and react to external disturbances of an extremely small magnitude. One class of such disturbances are the impacts of micrometeoroids or dust. A simple model of the LPF system suggests that individual impacts with transferred momentum exceeding a few tens of nanoNewton-meters will be detectable. Furthermore, the ability of LPF to resolve both the linear and angular momentum transfer as vector quantities allows information such as the sky location and the impact location to be estimated. This novel approach to micrometeoroid detection and characterization, as well as the location of LPF in the solar system, provide an opportunity to improve our understanding of the dust environment in the inner solar system. In this talk, I will give an overview of the detection process, present preliminary results from the detection pipeline, and discuss plans for the future.

• Wanner Gudrun
  ‹ Spacecraft motion pick-up in LISA Pathfinder’s acceleration measurement ›
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  Gudrun Wanner AEI Hannover Spacecraft motion pick-up in LISA Pathfinder’s acceleration measurement In the well known LISA Pathfinder acceleration measurement published in our primary paper (DOI 10.1103/PhysRevLett.116.231101), we showed a bulge in the noise curve resulting from pick-up of space craft motion. In two so called engineering days, we later aligned the test masses and thereby reduce this cross talk. We will show noise curves before and after the engineering days, explain the physical cross talk effects, the models used to compute the new test mass orientations and also the difficulties in doing such a hardware optimization of the acceleration noise curve.

• Wissel Lennart
  ‹ LISA Pathfinder: Understanding DWS noise for the LISA mission ›
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  Lennart Wissel AEI Hannover LISA Pathfinder: Understanding DWS noise for the LISA mission The LISA mission design needs to account for out-of-plane angles between the received and transmitted beams of the three satellites yielding readout noise in the differential wavefront sensing (DWS). This effect was investigated with LISA Pathfinder (LPF) through a designated investigation during the in-orbit operational phase. Stepwise slewing of one of the two free-falling test masses was commanded via the on-board electrostatic actuators, and the resulting noise in the differential interferometer between the two test masses was measured. The results of this investigation are presented, and plans for a consecutive LPF investigation to give an improved performance estimate of the DWS are discussed.

B) LISA Hardware

• Bai Yanzheng
  ‹ In-Orbit Feedback Control Verification of Electrostatic Accelerometer for Future applications of Inertial Sensors ›
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  Yanzheng Bai Huazhong University of Science and Technology In-Orbit Feedback Control Verification of Electrostatic Accelerometer for Future applications of Inertial Sensors High-precision electrostatic accelerometers were successfully used in satellite gravity missions to measure the Earth’s gravity field. In our group, space electrostatic accelerometer based on the capacitive sensors and electrostatic control technique has been investigated for space science research in China such as testing of equivalence principle (TEPO), searching non-Newtonian force in micrometer range, satellite Earth’s field recovery and so on. A flight model of electrostatic accelerometer has been tested in space for more than 2 years. The basic feedback control of 6 degrees of freedom of the test mass relative to the electrodes frame is successfully verified. Meanwhile some attitude variations and vibrations of the satellite are tested. It is important for designing and simulating the control of inertial sensor in TianQin project based on our developed Simulink models. This poster will show in orbit experiment results and discuss the applications for inertial sensors.

• Brugger Christina
  ‹ System performance of In-Field Pointing for eLISA ›
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  Christina Brugger Airbus DS GmbH System performance of In-Field Pointing for eLISA 1 Airbus DS GmbH, 88039 Friedrichshafen, Germany 2 Airbus DS GmbH, 82024 Taufkirchen, Germany 3 UK Astronomy Technology Centre Royal Observatory Edinburgh, Blackford Hill Edinburgh, EH9 3HJ. UK 4 TNO Opto Mechatronics, 2600 AD Delft, Netherlands Within the eLISA mission, orbital dynamics cause constellation-deviations from a unilateral triangle, exacting active compensation of the resulting annular variations of each apex angle. Traditionally, “Telescope Pointing” architectures actuate the entire telescope/interferometry/inertial sensor assemblies for each arm, hence requiring complex mechanisms and articulated phase referencing links between adjacent arms. "In-Field Pointing" (IFP), an alternative proposed by Astrium Satellites Germany, has the potential to significantly reduce the system complexity: Both telescopes are rigidly connected to a single optical bench, enabling a compact instrument architecture without articulated phase-link and eventually a more robust drag-free control. For each arm, a small beam-tilting mechanism is positioned into an intermediate pupil of a wide-field-of-view telescope. However, phase walk effects within the scanning range place demanding requirements on the telescope design and on the residual spectral noise of the mechanisms, necessitating early experimental investigation. Therefore, we implement a IFP system-testbed, co-funded by DLR. The all-Zerodur setup includes a pm-precision OH-bonded heterodyne interferometer, a representative +-1°-field-of-view 15-cm-aperture telescope and a prototype mechanism (TNO). Our goal is to verify the phase-performance within the measurement band for central elements of this LISA payload system option. We show preliminary measurements and report about the current status of the project.

• Cavet Cecile [ pdf ]
  ‹ A proto-data processing centre ›
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  Cecile Cavet François Arago Centre, APC, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité A proto-data processing centre The eLISA/NGO project preparation requires to study and define a new data analysis framework, capable of dealing with highly heterogeneous CPU needs and exploiting the emergent information technologies. In this context, we started to develop and provide a prototype of the mission’s Data Processing Centre (DPC). The DPC is designed to efficiently manage computing constraints and is also able to offer a common infrastructure where the collaboration-wide development work could start. Several tools such as continuous integration with Jenkins and code quality checks with Sonar have already been delivered to the collaboration (http://elisadpc.in2p3.fr/) and are used now for simulations and performance studies. We will present the progress made regarding this collaborative environment, and also discuss the possible next steps towards an on-demand computing infrastructure. This activity is supported by the CNES as part of the French contribution to eLISA.

• Di Fiore Luciano
  ‹ A two-stage torsion pendulum for ground testing free fall conditions on two degrees of freedom.  ›
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  Luciano Di Fiore INFN - Napoli A two-stage torsion pendulum for ground testing free fall conditions on two degrees of freedom. Ground testing with torsion pendulums played a key role in the development and characterization of the Gravitational Reference Sensor (GRS) of LISA-Pathfinder. We report on a torsion pendulum facility with 2 soft degrees of freedom (DOF), realized by off-axis cascading two torsion fibers. This instrument allows simultaneous measurement of force and torque acting on the suspended test mass, approaching free-fall condition on two DOFs down to a few mHz. It was developed for testing on two DOFs the LISA-Pathfinder GRS. We will report on the results of some measurement campaigns devoted in particular to the characterization of force to torque and torque to force actuation cross-talks. We will also analyze in some details advantages and drawbacks of a 2 DOF facility with respect to a single DOF pendulum, and discuss possible upgrades and application for the future LISA mission or for ground testing of other space experiments requiring drag-free control.

• Duan Hui-Zong
  ‹ Experimental Test of Sub-Picometer Heterodyne Laser Interferometer ›
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  Hui-Zong Duan TIANQIN Research Center for Gravitational Physics, SYSU Experimental Test of Sub-Picometer Heterodyne Laser Interferometer A heterodyne laser interferometer with quasi-monolithic structure and symmetric optical configuration is presented. Environmental fluctuation is one of the error sources which limit the measurement resolution of laser interferometer. The symmetric and balance configuration of optical path can decompress the temperature fluctuation. Besides, optical bench with quasi-monolithic structure has a great common-mode rejection of the ground vibration noise. Under the same experimental environment, we compare the common-path bonding interferometer with another ultra-stable Mach-Zenhder heterodyne laser interferometer made using hydroxide-catalysis bonding technique. From the experiment results, the temperature coupling coefficient of this common-path bonding laser interferometer is 285nm/K, which is much lower than the coefficient of ultra-stable Mach-Zenhder interferometer. The displacement measurement resolution of common path interferometer achieves 0.6pm/Hz1/2@1Hz.

• Fernández Barranco Germán
  ‹ Overview of photoreceivers in present and future intersatellite laser interferometry ›
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  Germán Fernández Barranco AEI Hannover Overview of photoreceivers in present and future intersatellite laser interferometry The particular conditions present in intersatellite laser interferometers set challenging requirements for the opto-electrical interface of the system, the photoreceiver. The Doppler shift created by the relative motion between the satellites requires high-speed electronics that can handle MHz signals while maintaining high phase fidelity with microradian precision in the case of LISA. Additionally, the detection of an incoming optical signal in the order of nW or pW needs a very low electronic noise contribution, in the order of a few pA/sqrt(Hz). We present the design and characterization of the photoreceiver developed for the GRACE-FO mission, as well as improved designs with heterojunction bipolar transistors for future intersatellite interferometers. Furthermore, simulations of the effect of non-uniform photodiode responses on the interferometer output have been conducted to study their influence on observables such as differential wavefront sensing and longitudinal phase. Using measured photodiode responses we can now predict these influences numerically, enabling a quantitative evaluation of photodiode candidates for future missions.

• Fitzsimons Ewan
  ‹ Optical Bench Design for L3 ›
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  Ewan Fitzsimons UK Astronomy Technology Centre Optical Bench Design for L3 As one of the core components in an interferometric gravitational wave observatory the Optical Bench (OB) is crucial for the success of L3. It interfaces directly to the test mass, the telescope and the far-spacecraft; as such its design and performance are highly dependent on a number of important considerations for the overall L3 observatory. We will: review how the top-level science requirements flow down to OB design considerations; discuss various L3 architecture options – such as arm length, backlink implementation, in-field pointing, point-ahead angle correction etc. – and how they could affect the OB design and performance; and describe the level of alignment accuracy and stability, in relation to what we achieved for the LISA Pathfinder OB, that is likely required to make L3 a success.

• Gehler Martin
  ‹ Activities and Technology Developments at ESA for L3 ›
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  Martin Gehler ESA Activities and Technology Developments at ESA for L3 A brief overview of the Agency’s current planning of the Gravitational Wave Observatory mission (L3) is given, along with information on the ongoing preparatory activities and technology developments. Currently scheduled for a launch in 2034, a Gravitational Wave Observatory mission is foreseen for the European Space Agency’s third large class mission (L3) within the Cosmic Vision 2015 - 2035 plan. Building upon experience from previous studies and, in particular, the successful LISA Pathfinder heritage, the Agency has begun to restart activities in preparation for the L3 mission.

• Gerberding Oliver
  ‹ Test mass readout using deep frequency modulation interferometry ›
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  Oliver Gerberding AEI Hannover Test mass readout using deep frequency modulation interferometry The laser interferometric readout of free floating test masses is one of the integral technologies for LISA and LISA Pathfinder. Typically these laser interferometers use heterodyne interferometry, with beat notes in the kHz or MHz range, where two single sideband beams are brought onto an optical bench and then interfered multiple times. This has to be done at least twice, once for subtracting common mode phase noise and once for performing the actual measurement. We present here the current status of the investigation of a new interferometry technique that simplifies test mass readouts by using only a single laser beam that is strongly modulated in frequency and then interfered with a delayed version of itself. In first experiments we have achieved $\textrm{pm}/\sqrt{\textrm{Hz}}$ level sensitivities in null measurements and we are currently preparing experiments to investigate the performance in ultra-stable interferometers implementing a two-sided test mass readout. For this purpose we have constructed a reference unequal arm length Mach-Zehnder interferometer for stabilizing the laser frequency, achieving levels below $100\,\textrm{Hz}/\sqrt{\textrm{Hz}}$ at $1\,$Hz. We also discuss our current understanding of the phase readout, which is done using a real-time non-linear fit algorithm, and its linearity and limitations in comparison to classic heterodyne interferometry.

• Gesa Boté Lluis [ pdf ]
  ‹ From LPF to eLISA: new approach in payload software ›
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  Lluis Gesa Boté Institut de Ciències de l'Espai (CSIC-IEEC) From LPF to eLISA: new approach in payload software eLISA will be the first observatory in space to explore the Gravitational Universe. It will gather revolutionary information about the dark universe. This implies a robust and reliable embedded control software and hardware working together. With the lessons learnt with the LPF DMU software as baseline, we will introduce in this poster the key concepts and new approaches that our group is working on in terms of software: multiprocessor, self-modifying-code strategies, 100% hardware and software monitoring, embedded scripting, Time and Space Partition.. etc. The poster will also list the challenges that those techniques will imply in space software development.

• Grado Aniello [ pdf ]
  ‹ An Optical Read-Out system for the LISA gravitational reference sensor: present status and perspectives. ›
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  Aniello Grado INFN/INAF An Optical Read-Out system for the LISA gravitational reference sensor: present status and perspectives. Since a few years, the LISA group in Napoli has been working to the development of an Optical Read-Out (ORO) system, based on optical levers and position sensitive detectors, for the LISA Gravitational Reference Tensor (GRS). This is intended as a more sensitive extra sensing device, in addition to capacitive readout that is the reference solution already tested on flight by the LISA-Pathfinder mission. The reliability of the proposed ORO device and the fulfillment of the sensitivity goals have been already demonstrated in bench-top measurements and tests with torsion pendulum facilities. In this paper we report on the present status of this activity, presenting the results obtained so-far and the perspectives for application for the future LISA mission.

• Halloin Hubert [ pdf ]
  ‹ Orbits optimization for (e)LISA ›
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  Hubert Halloin APC - CNRS / Université Paris Diderot Orbits optimization for (e)LISA The LISA constellation is subject to ‘breathing’ and ‘flexing’ effects, due to the varying distances between the satellites. These effects cause Doppler shifts, varying pointing angles and variable propagation delays which impact the mission design and the measurement performance. Flexing and breathing can be (semi-)analytically minimized for keplerian orbits, but the main perturbations are due to the Gravitational attraction of other celestial objects, mainly Earth and Jupiter, and therefore require numerical approach. We present here some results of orbit optimization for various (e)LISA configurations (i.e.the minimization of constellation’s breathing and flexing), taking into account the constraints on total launch mass (limiting the propellant mass) and maximum distance to Earth (telecommunication link budget).

• Hey Franz Georg
  ‹ Micro-Newton Propulsion Development and Testing for LISA ›
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  Franz Georg Hey Airbus Defence and Space Micro-Newton Propulsion Development and Testing for LISA In the context of investigations for an AOCS thruster sufficient for LISA, we have developed a highly precise thrust balance. The balance is part of our unique micro-Newton thruster test facility that is tailored for testing LISA micro-Newton thruster candidates. The facility allows us to test different micro propulsion systems such as the micro radio frequency ion thruster RIT\textmu X, or a micro Highly Efficiency Multistage Plasma Thruster (\textmu HEMPT). The thrust balance consists of two hanging pendulums. A sub-nm precision heterodyne laser interferometer serves as an optical read-out. The whole setup is a symmetric configuration enabling a common-mode rejection of the dominant noise sources. At frequencies as low as 1 mHz, the balance provides a demonstrated precision down to 0.1 \textmu N/Hz^1/2. The development of the \textmu HEMPT was carried out in parallel to the test facility development. Intensive tests demonstrated that the thruster could be a simple alternative thruster candidate for LISA. Beside the fully electrical operation, the thruster can be also used as xenon cold gas thruster which allows a dual mode operation depending on the required overall thrust. We will give an overview of our recent thruster and facility development including test results and the future plans.

• Hillsberry Daniel
  ‹ The UF LISA Optical Bench ›
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  Daniel Hillsberry University of Florida The UF LISA Optical Bench The LISA mission optical bench requires pm/sqrt(Hz) optical path stability in the 0.1 mHz to 1 Hz Band and long term alignment drifts at or below the micron and micro-radian levels. The bench material choice and design approach has always been a monolithic block of ultra-low CTE glass like Zerodur, with each optical component permanently hydroxide bonded. LISA would require over 10 complete units including spares, engineering models, and flight units. While LTP results show that this approach yields performance nearly two orders of magnitude below the requirements, this design makes the optical bench one of the highest risk items in terms of schedule and cost. The objective of our work is to explore the possibility of reducing both the cost and the manufacturing complexity of LISA's optical platforms through a ground-up redesign of the interferometer bench with an emphasis on modularization. The redesigned bench will minimize the necessary ultra-stable sections and allow a more conventional approach for the rest. Here we report on our initial efforts to identify high-quality commercial mounts for use in the new bench as well as initial stability and alignment measurements on a conventional molybdenum bench.

• Hollington Daniel
  ‹ Characterising and Testing Deep UV LEDs for Use in Space Applications ›
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  Daniel Hollington Imperial College London Characterising and Testing Deep UV LEDs for Use in Space Applications Deep ultraviolet (DUV) light sources are used to neutralise isolated test masses in highly sensitive space-based gravitational experiments. An example is the LISA Pathfinder charge management system, which uses low-pressure mercury lamps. A future gravitational-wave observatory such as LISA will likely use UV light-emitting diodes (UV LEDs), which offer numerous advantages over traditional discharge lamps. Here we report on a test campaign that was carried out to quantify the general properties of three types of commercially available UV LEDs and assess their suitability for use in space.

• Jin Gang
  ‹ A simulation of weak-light phase-locking for space laser interferometer ›
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  Gang Jin Institute of Mechanics,Chinese Academy of Sciences A simulation of weak-light phase-locking for space laser interferometer A comprehensive simulation was performed to better understand the impacts and effects of the additional technical noises on weak-light phase-locking for LISA. The result showed that the phase of the slave laser tracked well with the received transmitting light under different noise level, and the locking precision was limited by the phase readout noise when the laser frequency noise and clock jitter noise were removed. This result was then confirmed by a benchtop experimental test. The required LISA noise floor was recovered from the simulation which proved the validity of the simulation program. In order to convert the noise function into real time data with random characteristics, an algorism based on Fourier transform was also invented.

• Killow Christian
  ‹ Compact low-noise fibre-coupled displacement sensor suitable for GRS proof-mass sensing in space applications ›
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  Christian Killow University of Glasgow Compact low-noise fibre-coupled displacement sensor suitable for GRS proof-mass sensing in space applications Precision displacement sensing at the nm or better scale is an enabling element in a range of ground- and space-based applications – not least for the monitoring of the LISA Pathfinder test masses. To date, most measurements of inertial-sensor test mass motions have been made electrostatically. Achieved sensitivity is typically at the nm/sqrt(Hz) level at 1mHz, using sensing plates within a few mm of the test mass surfaces. A change to – or addition of – optical interferometry could have some distinct advantages: the displacement monitoring sensitivity and range could easily be improved by a significant factor, and interferometry would allow larger gaps between the test mass and its housing, potentially reducing the effects of spurious forces that can perturb test mass motion. We will report on the development and experimental demonstration of a fibre sensor with a noise floor of 0.01 nm/sqrt(Hz) and operating range of a few centimetres. At 1 mHz we have demonstrated sensitivity better than 0.4 nm/sqrt(Hz) – a factor of 5 more sensitive than the already impressive capacitive sensors used in LISA Pathfinder. The sensor is designed to be extremely small, readily space-qualifiable, and retrofitable to existing systems. In addition to its potential role in inertial sensors, the sensor could have many other space- and ground-based applications where sub-nm accuracy of displacement monitoring of mechanisms is required.

• Lieser Maike
  ‹ eLISA Optical Bench development - Testing interferometric imaging to reduce tilt-to-length coupling ›
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  Maike Lieser AEI Hannover eLISA Optical Bench development - Testing interferometric imaging to reduce tilt-to-length coupling Tilt-to-length coupling is one of the largest noise sources for eLISA. Imaging systems in front of the interferometer photo diodes are planned to suppress this tilt-to-length coupling. We successfully tested two different designs of imaging systems and compared their behavior to optical simulations. Both designs meet the eLISA requirement on tilt-to-length coupling suppression of 25µm/rad. For the testing we developed and built a setup consisting of two ultra-stable interferometer benches – one representing the Optical Bench in an eLISA spacecraft and one providing the beam received by the telescope and a reference interferometer. The setup provides conditions representative for the mission like a received beam with a flat intensity and phase profile and a Zerodur Optical Bench with bonded optics. It will be a versatile test bed for further optical bench development for eLISA.

• Loughlin Hudson
  ‹ Undergraduate LISA Research at NASA Goddard Spaceflight Center ›
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  Hudson Loughlin Princeton Undergraduate LISA Research at NASA Goddard Spaceflight Center This poster will describe some of the undergraduate efforts at Goddard to contribute to LISA research. In particular, it will summarize work with low noise quadrant photorecievers for wavefront sensing, occulting masks suitable for a secondary mirror for an on-axis telescope, contributions to ongoing off-axis telescope work, modeling and data analysis, among other subjects. In addition to the direct benefits to LISA, this undergraduate research fosters an interest in the mission and gravitational wave science and provides an avenue for undergraduates to become a part of the next generation of researchers in this field.

• Luo Yingxin
  ‹ Progress on development of a laser frequency stabilization prototype for spaceborne interferometry ›
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  Yingxin Luo TianQin Research Center, Sun Yat-Sen University Progress on development of a laser frequency stabilization prototype for spaceborne interferometry Recent progress of a laser frequency stabilization prototype for inter-satellite laser ranging is presented in this talk. In this prototype, the Pound-Drever-Hall (PDH) method is used to stabilize the laser frequency to an ultra-stable Fabry-Pérot cavity. The cavity and its mode-matching optical layout are integrated into a quasi-monolithic optical bench that is made of ultra-low expansion (ULE) materials and fabricated by hydroxide-catalysis bonding technique. The optical and geometric parameters of the optical bench have been optimized to ensure the TEM00 mode-matching efficiency and to minimize the vibration sensitivity of the cavity. All-fiber devices are applied for the PDH optical link. An in-house-designed digital controller has been developed based on FPGAs for automatic laser frequency locking. The optical bench is installed in a vacuum chamber with 10^-7 mbar level of pressure and its surrounding temperature is actively controlled within 0.6 mK. Active vibration isolation is used to suppress the seismic noise to 10^-7g/Hz^1/2 during testing on ground. Preliminary results of beat note analysis shows that the laser frequency noise of this prototype is less than 30 Hz/Hz^1/2 from 0.7 Hz to 10 Hz. Updated results will be presented in the conference.

• Mance Davor [ pdf ]
  ‹ GRS Electronics for a Space-Borne Gravitational Wave Observatory ›
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  Davor Mance ETH Zürich, Institute of Geophysics GRS Electronics for a Space-Borne Gravitational Wave Observatory The Gravitational Reference Sensor (GRS) electronics is a crucial element of the future space-borne gravitational wave observatory. Together with the Laser Metrology System, it provides position measurements of the sensor’s reference body, a Test Mass (TM), for all axes. This is needed for precise spacecraft control. In addition, the GRS electronics can actuate the TM using electrostatic forces, which is used to get or to keep the TM centered in its enclosure or to follow a certain guidance. The GRS electronics, also called the Inertial Sensor Front End Electronics (IS FEE), is successfully tested during the LISA technology verification mission, i.e. the LISA Pathfinder, launched in December 2015. This mission is still ongoing till the completion of the mission extension period in May 2017. The electronics is designed in Switzerland by RUAG and HES-SO under supervision of ETH Zürich and University of Zürich. The poster describes the working principle and the adopted technical solutions for the electronics for the two main functions, TM sensing and actuation. In particular, focus is on key performance drivers of the sensing front-end circuit, the sensing injection signal generation and the voltage reference design. The latter is particularly critical for the stability of the actuation circuits. The additional designs of key circuits on route to LISA, that were already tested on ground, are shown as well. The GRS electronics performance, as verified in space, is compared with the results from ground measurements.

• Mandel Oliver
  ‹ Optical metrology terminal for satellite-to-satellite laser ranging ›
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  Oliver Mandel Airbus DS GmbH Optical metrology terminal for satellite-to-satellite laser ranging Interferometric laser ranging is a promising technology for satellite-to-satellite tracking within the content of earth observation, gravitational wave detection, or formation flying. Different design approaches for a heterodyne dynamic laser ranging instrument to be utilized in a next generation gravity mission with nanometer accuracy have been evaluated and are compared in terms of performance, compactness, flexibility, and complexity. Environmental influences that affect the measurement performance are assessed on the basis of measurement data and mission studies related to satellites in a low earth orbit. For enabling larger inter-spacecraft distances the instrument designs include a transponder system, which necessitates a 2-dimensional beam steering mechanism and, moreover, is not part of the measurement path. A monostatic instrument design with the external beams propagating on the line of sight, but comprising a bistatic concept internally using a compact corner cube retroreflector, is presented together with a dedicated test metrology setup. In order to facilitate the accommodation in future satellite missions, the design allows for a continuously adjustable distance between the optical bench and the position of its phase center. Besides, the instrument can be built on a single optical bench with a compact size and good thermal coupling to the satellite's structure.

• Marin-Matholaz Etienne
  ‹ Control System environment for eLISA V&V phase ›
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  Etienne Marin-Matholaz CNRS - APC Control System environment for eLISA V&V phase The verification and validation phase of the eLISA mission will consist in the calibration, characterization and qualification of the different subsystems of the eLISA mission. It will require the setup of test-benches, mastered by a Control software able to perform data acquisition, monitoring and storage on various and heterogeneous test-benches, for an extended period of time. In this context, the APC laboratory already set up a private network for test-benches instruments, and we will present a control system able to control various instruments (acquisition instruments, power supplies, ...) through the network. It is already in use for the testing phase of the LSST project (https://www.lsst.org/), and it provides the required features such as a simple development framework for the test-bench software design, the ability to control test bench through consoles, graphic interface or scripting, real time visualization of data acquisition and database recording of those acquisitions.

• Mateos Ignacio
  ‹ Technology demonstrator of a magnetic measurement system for space-based gravitational wave observatories ›
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  Ignacio Mateos Institut de Ciències de l'Espai (CSIC-IEEC) Technology demonstrator of a magnetic measurement system for space-based gravitational wave observatories Space-borne gravitational wave detectors such as eLISA entail a thorough knowledge of the spacecraft magnetic field since the on-board experiment can only operate propitiously under specific magnetic environmental constraints. Hence, with the purpose of estimating the forces arising from magnetic effects, magnetometers are necessary devices to monitor the fluctuating magnetic field inside the satellite. A simplified flight model of the currently proposed magnetic measurement system for eLISA has been integrated in a CubeSat so as to increase the technology readiness level (TRL) of the instrument. Since the magnetometers on board the demonstrator will be located within a magnetic shielding, the in-flight tests will make it possible to characterize the low-frequency noise behavior of the system in space environmental conditions. The payload fills less than 0.05U of the 6U CubeSat, which is expected to be launched along the second half of 2016. This talk will sketch out the principal characteristics of the instrument embarked in the 3Cat-2 CubeSat leading towards the improved magnetic measurement system for eLISA.

• Meshksar Neda
  ‹ FEE-Simulator for LISA ›
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  Neda Meshksar ETH Zürich FEE-Simulator for LISA At ETH Zurich we are developing a modular simulator that provides a realistic simulation of Front End Electronics (FEE) for LISA. It is based on the FEE-simulator already implemented for LISA Pathfinder. It considers, in particular, the non-linearity and the critical details of hardware, such as the non-linear multiplicative noise caused by voltage reference instability, test mass charging and detailed actuation and sensing algorithms. We will present the simulation modules, considering the above-mentioned features. We aim to develop the non-linear FEE-simulator in LISA-Dyn simulator and finally to integrate it in LISA Code.

• Ming Li
  ‹ The technical challenges of space gravitational wave detector ›
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  Li Ming DFH SATELLITE CO., LTD The technical challenges of space gravitational wave detector The detection of gravitational wave space is the focus of the current international research. This paper introduces the detection basic principles and mainstream solutions, From the demand of scientific task,analysis and obtained the scientific problem which the engineering need to solved. On the base of three problems and from aspect of the spacecraft development, through analysis and simulation, give the preliminary solution and technical index. Combined with the existing technical development level, Present the challenges of spacecraft development .

• Olatunde Taiwo
  ‹ UV-LEDs for LISA test mass charge control ›
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  Taiwo Olatunde University of Florida UV-LEDs for LISA test mass charge control UV-LEDs for LISA test mass charge control Taiwo Olatunde, Stephen Apple, Andrew Chilton, Michael Aitken, Giacomo Ciani, Guido Mueller, John W. Conklin The residual test mass accelerations in LISA must be below 3 fm/𝑠2/√Hz at all frequencies between 0.1 and 3 mHz. Test mass charges coupled with stray electrical potentials and external electro-magnetic fields is a well-known source of acceleration noise. LISA Pathfinder uses Hg lamps emitting mostly around 254 nm to discharge the test masses via photoemission, but a future LISA mission launched around 2030 will likely replace the lamps with newer UV LEDs with lower mass, better power efficiency, smaller size and higher bandwidth. This presentation will discuss charge control demonstrated on the torsion pendulum at the University of Florida using latest generation UV LEDs producing light at 240 nm with energy above the work function of pure Au. Initial results of Au quantum efficiency measurements (number of emitted electrons per incident photons) which is critical for bi-polar charge control will also be presented.

• Penkert Daniel [ pdf ]
  ‹ An Optical Testbed for the LISA Arm Metrology Chain ›
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  Daniel Penkert AEI Hannover An Optical Testbed for the LISA Arm Metrology Chain As LISA will utilize cascaded heterodyne laser interferometry with highly dynamic beat-note signals between roughly 5 and 25 MHz, the planned readout mechanism relies on FPGA-based digital phasemeter hardware capable of tracking these beat-notes with microcycle precision. We present our quasi-monolithic “Hexagon” interferometer, a key experiment for testing and advancing our prototype phasemeter technology, which uniquely combines two vital aspects into a single experimental setup: (1) It implements an optical three-signal generator capable of producing beat-note signals whose frequency sum should vanish as long as the three individual signals’ phases are properly tracked. (2) It represents a simplified and rigid miniature version of a three-spacecraft LISA constellation, which can be used to not only reproduce most sources of optical and electronic noise, but rather to simulate the full LISA arm metrology chain, i.e. inter-spacecraft clock tone transfer, PSN ranging, and data communication. To this end, we are planning to expand the current experiment by using three fully independent phasemeter systems, connected to each other only via phase modulations modulated onto each of the interferometer’s three input beams. These modulations include GHz sidebands generated by each frequency distribution system, a core metrology system to achieve the necessary constellation wide clock stability.

• Perreur-Lloyd Michael [ pdf ]
  ‹ First steps towards automated optical bench assembly for eLISA ›
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  Michael Perreur-Lloyd University of Glasgow First steps towards automated optical bench assembly for eLISA The optical benches (OB) envisaged for eLISA are significantly more complex and numerous than the single bench developed for LISA Pathfinder. Constructing each eLISA bench is expected to involve hydroxide catalysis bonding of both a higher quantity and higher density of optical components than has been previously attempted. To address this challenge and at the same time reduce risk and reduce assembly time, we have been working towards a more automated bonding approach. We present the current state of our developments which include interferometric readout of component-to-baseplate angular orientations as a component is brought to the point of bonding. We will outline the achieved bonding accuracy and speed of the overall process and compare this with our experience of building the LPF OB. We will then discuss our plans for further developments that will result in a full eLISA OB assembly facility.

• Sanjuan Josep
  ‹ GRACE Follow-on OGSE and testing ›
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  Josep Sanjuan DLR GRACE Follow-on OGSE and testing The Gravity Recovery and Climate Experiment (GRACE) has been mapping the Earth's gravity field changes since 2002 and now is at the end of its life-time. Due to the importance of the GRACE satellites, a follow-on mission will be launched in 2017, which will include a Laser Ranging Interferometer (LRI) as a technological demonstrator. The LRI shares many technologies and requirements with the LISA mission and will be the first inter-satellite laser link in space. This poster describes the optical ground support equipment (OGSE) needed to test the LRI key subsystems and the results of different test campaigns with engineering model and flight model hardware.

• Sankar Shannon
  ‹ Progress with a prototype telescope for space-based gravitational wave observation ›
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  Shannon Sankar NASA GSFC / CRESST / USRA Progress with a prototype telescope for space-based gravitational wave observation The LISA telescope is a crucial part of the long arm measurement. The requirements for the telescope are governed by the observatory-level noise allocations as well as mission-level system design. Based on reasonable choices for these parameters with eLISA as a reference mission, we have designed, fabricated and studied a prototype version of the telescope. We have also developed detailed models of the telescope performance. I will discuss these studies in detail and elaborate, in particular, on the scattered light performance of this prototype design. Furthermore, I will discuss ongoing plans for improving on the current prototype to develop a more flight-like telescope with very close attention paid to dimensional stability and to interfacing with the optical bench.

• Schuldt Thilo
  ‹ Iodine frequency references for space ›
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  Thilo Schuldt DLR Bremen, Germany Iodine frequency references for space Optical frequency references are a key element for the realization of future space missions. They are needed for missions related to tests of fundamental physics, gravitational wave detection, Earth observation and navigation and ranging. In missions such as GRACE follow-on or eLISA the optical frequency reference is used as light source for high-sensitivity inter-satellite distance metrology. While cavity-based systems are current baseline e.g. for eLISA, frequency stabilization on a hyperfine transition in molecular iodine near 532nm is a promising alternative. Due to its absolute frequency, iodine standards crucially simplify the initial SC acquisition procedures. Current setups fulfill the GRACE-FO and eLISA frequency stability requirements and are realized near Engineering Model level. We present the current status of our developments on Elegant Breadboard and Engineering Model level taking into account specific design criteria for space compatibility such as compactness (size iodine spectroscopy EM: 38$\times$18$\times$10cm$^3$) and robustness. Both setups achieved similar frequency stabilities of $1\cdot 10^{−14}$ at an integration time of 1s and below $5\cdot 10^{−15}$ at integration times between 10s and 1000s. Furthermore, we present an even more compact design currently developed for a sounding rocket mission with launch in 2017.

• Suemasa Aru
  ‹ Developments of highly-stabilised lasers for DECIGO/Pre-DECIGO ›
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  Aru Suemasa Insitute for Laser Science, Univ. of Electro-communications Developments of highly-stabilised lasers for DECIGO/Pre-DECIGO In Japan, the space gravitational wave detector, DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) and Pre-DECIGO have been promoted whose main observation target is GW from early universe below 1Hz. In order to realize their extremely high strain sensitivity of δL/L<10^-23 at the observation band, we have developed frequency and intensity stabilized lasers whose output power is higher than 10 W around 515 nm, and whose frequency noise should be δf<0.5 Hz/√Hz, and intensity noise should be δI/I<10^-8 /√Hz at 1 Hz. We have developed two breadboard models (BBM2 and BBM3) of the iodine-stabilized Yb-doped fiber laser whose frequency is locked to saturated absorption lines of I2 around 515 nm, and whose noise was suppressed down to 0.4 Hz/√Hz at 1 Hz evaluated from the errors signal. The intensity stabilization at 1 Hz was realized by controlling the intensity of pump power for the Yb-doped fiber amplifier (YDFA), and whose out of loop intensity noise was successfully suppressed down to 10^-7 /√Hz level. In this workshop, we will report the recent developments of our I2-stabilized lasers for DECIGO/Pre-DECIGO and the future prospects for increasing the output power of our laser up to 10 W.

• Torrents Rufas Alejandro [ pdf ]
  ‹ An ultra-stable thermostat to explore optical metrology in the low-frequency regime ›
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  Alejandro Torrents Rufas (Institut de Ciències de l'Espai (CSIC-IEEC)) An ultra-stable thermostat to explore optical metrology in the low-frequency regime Current research aiming at testing fundamental physics, like measuring gravitational waves, require environments being highly stable over long periods in order to achieve high precision in the low frequency, i.e. the millihertz band. Temperature noise is the main contribution in these time scales and therefore it needs to be either suppressed or actively compensated. In this contribution we present the development of a Mach-Zehnder interferometer into an ultra-stable thermal environment. The interferometer set-up is based on the deep phase modulation scheme where the demodulation step takes place in a FPGA with a LEON3 soft-core processor. In order to study the noise contributions in the low-frequency regime, the interferometer is located in a vacuum chamber and inside a passive thermal shield. Moreover, an active control is also applied to reduce laboratory perturbations. Here we report the thermal characterisation of our thermostat by means of a series of applied thermal injections and the first results of our set-up.

• Wang Zhi
  ‹ Telescope in space ›
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  Zhi Wang Changchun Institute of Optics, fine Mechanics and Physics,Chinese Academy of Sciences Telescope in space

• Xu Peng [ pdf ]
  ‹ Precision Measurement of Gravitomagnetic field and Laser Interferometry in Space ›
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  Peng Xu Academy of Mathematics and Systems Science, Chinese Academy of Sciences Precision Measurement of Gravitomagnetic field and Laser Interferometry in Space To pave way for a Chinese mission to detect gravitational waves in space, two pathfinder missions to test certain key technologies in space are discussed. The feasibility of performing additional precision measurement of the Earth/Moon gravitomagnetic field (frame dragging effect) during the pathfinder missions is explored. In one scheme, a planar gradiometer with one axis aligned along the along track direction and another axis orthogonal to the orbital plane is studied. A resonant signal generated by the differential signals between the relativistic precessions of the orbital plane and that of the orientation of the local free-falling frame is read out in terms of laser interferometry. In the second scheme, in a LL-SST mission to detect temporal variation of the Earth gravity field, the Sagnac like optical configuration of the Laser ranging instrument is employed to read out the accumulated phase difference between two counter propagating laser beams generated by the Earth gravitomagnetic field.

• Yan Hao [ pdf ]
  ‹ A dual-heterodyne laser interferometer for simultaneous measurement of linear and angular displacements ›
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  Hao Yan Huazhong University of Science and Technology A dual-heterodyne laser interferometer for simultaneous measurement of linear and angular displacements Picometer laser interferometry is an essential tool for ultra-precision measurements in frontier scientific research and advanced manufacturing. we present a dual-heterodyne laser interferometer for simultaneously measuring linear and angular displacements with resolutions of picometer and nanoradian, respectively. By implementing a dual-heterodyne interferometer with a highly symmetric optical configuration, low frequency noises caused by the environmental fluctuations can be suppressed to very low levels via common-mode noise rejection. Experimental results for the dual-heterodyne interferometer configuration presented demonstrate that the noise levels of the linear and angular displacement measurements are approximately 1 pm/Hz1/2 and 0.5 nrad/Hz1/2 at 1 Hz.

• Yang Fangchao
  ‹ Current Progress of Patch Effect Measurement Using an Electrostatic Controlled Torsion Pendulum with a Scanning Probe ›
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  Fangchao Yang Huazhong University of Science & Technology Current Progress of Patch Effect Measurement Using an Electrostatic Controlled Torsion Pendulum with a Scanning Probe The surface potential variation produces force and force gradient between the proof mass and electrodes and has been identified as a significant error source in terrestrial or space-borne gravitational experiments. To measure the charge distribution and its variation with better precision and higher resolution, we present an electrostatic-controlled torsion pendulum with a scanning conducting probe. This novel scheme combines the scanning capability of the Kelvin probe and the high precision of the torsion pendulum. Depending on our apparatus, the temporal and spatial variation of the surface potential can be measured.. This poster will show the progress on the patch effect measurement using an electrostatic controlled torsion pendulum.

• Yin Hang
  ‹ Current progress of ground test for inertial sensor by a single-stage torsion pendulum ›
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  Hang Yin Huazhong University of Science and Techology Current progress of ground test for inertial sensor by a single-stage torsion pendulum In order to investigate the surface and body effect of the test mass for inertial sensors, in our group, a single-stage electrostatically controlled torsion pendulum with suspending a massive test mass with kg level weight has been developed. The test mass is monitored by a high-precision capacitive position sensor, and is synchronously controlled by the electrostatic actuators. So it can be used to test the residual disturbance of the test mass on ground. The preliminary experiments results are present in this poster. It also will help us to investigate the surface and body effect of the actual test mass in the future based on this apparatus.

• Yu Jianbo
  ‹ Seismic Noise Suppression for Ground-Based Investigation of Inertial Sensors by Suspending the Electrode Cage ›
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  Jianbo Yu Huazhong University of Science & Technology Seismic Noise Suppression for Ground-Based Investigation of Inertial Sensors by Suspending the Electrode Cage Torsion pendulum has been widely employed to investigate the performance of an inertial sensor where the test mass is suspended by a thin fiber to compensate its weight. For many high precision ground-based experiments, seismic noise is a prominent source. This poster presents the design and performance of a suspension method with a two-stage torsion pendulum dedicated to high precision space accelerometers or inertial sensors. By suspending the electrode cage, the seismic noise coupling has been suppressed roughly four orders of magnitude.

• Zhang Jingyi
  ‹ Modeling & Simulation for inter-satellite laser link acquisition ›
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  Jingyi Zhang Huazhong University of Science and Technology Modeling & Simulation for inter-satellite laser link acquisition We present the scheme and the preliminary results of an inter-satellite laser link acquisition system that is designed for the next-generation gravity satellite mission. In this scheme of laser link acquisition, we use differential power sensing to establish the spatial acquisition, then use FFT peak detection algorithm with laser frequency tuning to establish the frequency acquisition. The signal acquisition process is simulated by Optical Simulation software developed based on Matlab in order to verify the validity of automatic spatial scans and alignment. An experimental prototype system has also been constructed to test the performance of the acquisition scheme, which contains initial misalignment of laser beams and attitude jitter of satellites. Both of the numerical and experimental results are presented in this talk.

• Zhou Zebing
  ‹ Current Progress and Development of Inertial Sensor for TIANQIN Project ›
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  Zebing Zhou Huazhong University of Science and Technology Current Progress and Development of Inertial Sensor for TIANQIN Project TIANQIN is a proposal for a space-borne detector of gravitational waves in the millihertz frequencies. The preliminary design including the inertial sensor has been reported in the TIANQIN project paper. In our group, some key technologies and ground performance tests of inertial sensors based on a two-stage torsion pendulum have been studied and developed for more than ten years. This talk will present recent progress on inertial sensors. Firstly, in order to further suppress the seismic noise, a new two-stage torsion pendulum scheme with a very dedicated vibration isolation scheme by suspending the vacuum chamber and suspending the electrodes are being constructed. Secondly, a massive TM with the mass of kg level has been suspended by a silicon fiber to investigate the body effect of the inertial sensor. Thirdly, an electrostatic-controlled torsion pendulum with a scanning probe has been set up to study the temporal and spatial variations of the surface potential on the TM. Preliminary experimental results on these aspects and future plan will be presented in this talk.

C) Astrophysics with Gravitational Waves

• Baker John
  ‹ Bayesian treatment of prospective LISA parameter estimation for massive black hole mergers ›
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  John Baker NASA-Goddard Space Flight Center Bayesian treatment of prospective LISA parameter estimation for massive black hole mergers A full understanding of LISA's science capability will require accurate models of incident waveform signals and the instrumental response. While Fisher matrix analysis is useful for some estimates, a full Bayesian treatment is needed for important cases at the limit of LISA's capability. We apply fast analysis algorithms enabling accurate treatment with EOB waveforms and the full-featured LISA response to study the significance of higher spherical harmonics and mergers in LISA analysis.

• Bondarescu Ruxandra
  ‹ Exploring the Spacetime with Atomic Clocks ›
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  Ruxandra Bondarescu University of Zurich Exploring the Spacetime with Atomic Clocks With the recent improvement in the accuracy and stability of atomics clocks and the links that connect them, it is becoming possible to use general relativity as a tool. Here we discuss (1) how tests of higher order general relativistic effects via space-craft tracking around the gas giants provide an independent measurement of their interior physics, and (2) the potential of atomic clock networks for gravitational wave detection. Gravitational waves perturb space-time introducing delays in the light travel time between clocks. Any two separated clocks can thus act as a gravitational wave detector. We present our preliminary results and show that under the assumption that the clock noise dominates other sources of noise, a network of clocks could reach sensitivities to gravitational waves of frequencies in-between the LISA and pulsar timing band, which are not accessible to other detectors.

• Breivik Katelyn [ pdf ]
  ‹ Distinguishing Between Formation Channels for Binary Black Holes with LISA ›
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  Katelyn Breivik Northwestern University Distinguishing Between Formation Channels for Binary Black Holes with LISA The recent detections of GW150914 and GW151226 imply an abundance of stellar-mass binary-black-hole mergers in the local universe. While ground-based gravitational-wave detectors are limited to observing the final moments before a binary merges, space-based detectors, such as the Laser Interferometer Space Antenna (LISA), can observe binaries at lower orbital frequencies where such systems may still encode information about their formation histories. We explore the parameters of millihertz band binary black holes formed in isolation in galactic fields and in dense stellar environments such as globular clusters. Overall we find three populations that may be distinguishable by LISA. We note a bimodality in the eccentricities of binary black holes evolved in isolation that could provide detailed constraints on the physics of black-hole natal kicks and common-envelope evolution. Finally, we show how the measurement of both chirp mass and eccentricity can be used to constrain formation channels for binary black holes.

• Ferrigno Carlo
  ‹ Searching gamma-ray counterparts of gravitational wave events with INTEGRAL ›
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  Carlo Ferrigno ISDC, University of Geneva Searching gamma-ray counterparts of gravitational wave events with INTEGRAL Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we put tight upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914 and LVT 151012, discovered by the LIGO/Virgo collaboration. The omni-directional view of the INTEGRAL/SPI-ACS has allowed us to constrain the fraction of energy emitted in the hard X-ray electromagnetic component for the full high-probability sky region of LIGO/Virgo trigger. Our upper limits on the hard X-ray fluence at the time of the event range from constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the Our team has a memorandum of understanding to follow-up possible triggers issued in near real time from the analysis of the gravitational wave teams.

• Gopakumar A
  ‹ Accurate measurement of black hole spin from the predicted GR centenary flare in OJ287  ›
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  A Gopakumar TIFR, Mumbai, India Accurate measurement of black hole spin from the predicted GR centenary flare in OJ287 The blazar OJ287 is the most promising candidate for a spinning supermassive black hole binary inspiralling under the action of gravitational radiation reaction. This is because the blazar exhibits prominent outbursts that are inherent in such an binary black hole model, which predicted a major optical outburst in 2015 December. The outburst did occur within the expected time range, peaking on 2015 December 5 at magnitude 12.9 in the optical R-band. Detailed Swift/XRT satellite observations and optical polarization data revealed the presence of a major thermal component in the flare . Its timing provided an accurate estimate for the spin of the primary black hole to be $0.313 \pm 0.01 $. This accurate measurement opens up the possibility of testing the black hole no-hair theorem with 10% accuracy during the present decade.

• Haney Maria
  ‹ Ready-to-use GW templates for eccentric inspirals ›
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  Maria Haney Tata Institute of Fundamental Research, Mumbai Ready-to-use GW templates for eccentric inspirals Inspiraling compact binaries with non-negligible orbital eccentricities are plausible gravitational wave (GW) sources for ground- and space-based GW detectors. As has been argued recently, a large fraction of binaries with non-zero eccentricity are potentially observable as they evolve through the LISA band, especially at low frequencies. Such observations could help distinguish possible formation channels for binary black hole (BBH) mergers like GW150914 and GW151226. In this talk, we present ready-to-use GW templates for compact binaries inspiraling along eccentric orbits, recently developed for the aLIGO data analysis software. Our eccentric waveform families provide fully analytic, post-Newtonian (PN) accurate interferometric response functions, both in the time and frequency domain. We also briefly discuss the implications of non-negligible eccentricity on the data analysis of the BBH merger events observed by aLIGO.

• Kamai Brittany
  ‹ Testing Fundamental Properties of Space with the Fermilab Holometer ›
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  Brittany Kamai Fermilab / Caltech Testing Fundamental Properties of Space with the Fermilab Holometer Precision length measurements provide valuable insights about the fundamental properties of space-time. The Holometer is a research program to both experimentally probe signatures of the Planck scale and to extend the accessible frequency range from kHz up to MHz for gravitational wave searches. The instrument consists of separate yet identical 39-meter Michelson interferometers operated at Fermi National Accelerator Laboratory, which can reach length sensitivities better than $10^{-20} \rm{m} /\sqrt{\rm{Hz}}$ within the 1-10 MHz frequency range. The Holometer is fully operational with 100s of hours of science quality data obtained during observational campaigns. I will discuss the first sets of results along with future directions of the experiment.

• Larson Shane
  ‹ Studying Variance in the Galactic Ultra-compact Binary Population ›
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  Shane Larson Northwestern U/Adler Planetarium Studying Variance in the Galactic Ultra-compact Binary Population In the years preceding LISA, Milky Way compact binary population simulations can be used to inform the science capabilities of the mission. Galactic population simulation efforts generally focus on high fidelity models that require extensive computational power to produce a single simulated population for each model. Each simulated population represents an incomplete sample of the functions governing compact binary evolution, thus introducing variance from one simulation to another. We present a rapid Monte Carlo population simulation technique that can simulate thousands of populations on week-long timescales, thus allowing a full exploration of the variance associated with a binary stellar evolution model.

• Petiteau Antoine [ pdf ]
  ‹ The simulation working group: toward an end-to-end simulator for LISA ›
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  Antoine Petiteau APC - Université Paris-Diderot The simulation working group: toward an end-to-end simulator for LISA Since beginning 2014, a number of scientists from the LISA community group their effort to develop an end-to-end simulator for LISA. Four workshops took place and today this very active "simulation working group" gathers a wide range of expertise on LISAPathfinder, LISA instrumentation, waveform modeling, data processing and data analysis. The objectives are multiples: develop a first version of the mission simulator, provide a tool for quick studies of various LISA configurations and provide tools for controlling the performances during the building of the instrument. After studying the models of the various subsystems and the data preprocessing methods, we define a modular structure for the simulator based on a generalized buffer system. We are developing the first version of the end-to-end simulator using the existing simulator LISACode as a starting point and the framework provided by the eLISA proto Data Processing Center. In parallel, other simulators are used for detailed studies like the dynamics with LISADyn and TDI with TDISim. In this talk, we will report the goals and the activities of the simulation working group. The on-going and future developments will be presented.

• Seto Naoki
  ‹ Prospects of eLISA for Detecting Galactic and extra-Galactic Binary Black Holes ›
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  Naoki Seto Kyoto University Prospects of eLISA for Detecting Galactic and extra-Galactic Binary Black Holes We discuss the prospects of eLISA for detecting gravitational waves (GWs) from binary black holes (BBHs) similar to GW150914. For a comoving merger rate that is consistent with current observation, eLISA is likely to identify both Galactic and extra-Galactic BBHs with sufficient signal-to-noise ratios. We also discuss astrophysical implications for the BBH detection.

• Wang Yan
  ‹ Detection and parameter estimation of continuous GW signals in pulsar timing arrays ›
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  Yan Wang Huazhong University of Science and Technology Detection and parameter estimation of continuous GW signals in pulsar timing arrays Pulsar Timing Array (PTA) based gravitational wave (GW) detection offers the exciting prospect of opening the very low frequency band of GW astronomy, complementing the high frequency band that has already been opened by ground-based detectors and the intermediate frequency band that will be opened by future space-based detectors. Supermassive black hole binaries are one of the primary targets of GW searches using PTAs. GW signals from such systems are well represented by parameterized models, allowing the standard Generalized Likelihood Ratio Test (GLRT) to be used for their detection and estimation. In this talk, we report the study of the performance of an approach where the pulsar phases are maximized semi-analytically under the general framework of GLRT (Wang et al., 2015). This approach is scalable since the number of parameters left for numerical optimization does not depend on the size of the PTA. The scalability of the method allows to add more pulsars to the array. This is demonstrated explicitly by using a large array of pulsars in the PTA that is expected in the SKA era.

D) Extreme Mass Ratio Inspirals

• Berry Christopher [ pdf ]
  ‹ Understanding the importance of transient resonances in extreme mass ratio inspirals ›
  [ close ]

  Christopher Berry University of Birmingham Understanding the importance of transient resonances in extreme mass ratio inspirals Extreme-mass-ratio inspirals occur when a compact object orbits a much larger one, e.g. a solar-mass black hole about a supermassive black hole. Many thousands of orbits could be measured using a space-based gravitational-wave detector, making these inspirals exquisite probes of the structure of the massive objects spacetime. As the inspiral progresses, the orbital frequencies evolve. If the radial and polar frequencies become commensurate, the system passes through a transient resonance. Resonances may be a generic feature of inspirals, but are not currently included in waveform templates. Resonance can cause a jump in the evolution of the orbital parameters, and I will explain how this can be intuitively understood. I will also look at the implications of resonances on detectability of inspirals with eLISA.

• Chua Alvin [ pdf ]
  ‹ Improving kludge waveforms for EMRIs ›
  [ close ]

  Alvin Chua Institute of Astronomy, Cambridge Improving kludge waveforms for EMRIs We introduce an improved EMRI waveform approximant designed for robust use in the next round of mock LISA data challenges. It is based on the well-known model by Barack and Cutler, which dephases relative to more accurate waveforms within hours due to its mismatched radial, polar and azimuthal frequencies. The new waveform uses a frequency map to the correct Kerr frequencies, along with updated evolution equations and trajectory fitting. It stays phase-coherent with more accurate waveforms for months, while matching the computational affordability of the Barack-Cutler model.

• F. Sopuerta Carlos
  ‹ Some studies on the EMRI event rate ›
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  Carlos F. Sopuerta Institut de Ciències de l'Espai (CSIC-IEEC) Some studies on the EMRI event rate We will describe some recent results on the production of Extreme-Mass-Ratio Inspirals (one of the main source of gravitational wave for LISA) via the astrophysical mechanism of capture. In particular the impact of the spin of the black hole and the relevance of the Schwarzschild barrier.

• Gair Jonathan [ pdf ]
  ‹ Overcoming noise uncertainty in eLISA parameter estimation ›
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  Jonathan Gair University of Edinburgh Overcoming noise uncertainty in eLISA parameter estimation The true power spectral density (PSD) of the noise in the eLISA data stream will not be known a priori. However, research on eLISA data analysis to date has typically assumed that the PSD of the detector is a known function. If that assumption is relaxed, then both the form of the PSD and the parameters of any signals present must be simultaneously estimated from the measured data. In this talk, we present some preliminary investigations of the impact of marginalising over the noise-uncertainty on the signal parameter estimation. Under reasonable assumptions, the noise-marginalisation can be performed analytically and the effect is to replace the usual likelihood on the parameters of the signal with an alternative noise-marginalised likelihood. We will describe how noise marginalisation could impact parameter recovery for eLISA sources, and discuss directions for future research on this important topic.

• Heffernan Anna [ pdf ]
  ‹ The Self-Force for Non-Geodesic Motion ›
  [ close ]

  Anna Heffernan University of Florida The Self-Force for Non-Geodesic Motion The self-force uses a perturbation of Einstein's field equations in the mass ratio to describe the motion of a point particle in a background spacetime. In compact body systems, EMRIs can be modelled as a point mass in Kerr spacetime making them an ideal application. We calculate the self-force of a particle with non- geodesic motion in two parts: regularization and computation. For the former, by the mode-sum approach we give the required, previously unknown regularization parameters, as well as higher-order terms that increase the mode-sum convergence rate. For computing the latter, we consider accelerated circular and bound eccentric orbits calculated in the frequency-domain. We discuss how the 'memory' of the self-force can be probed by considering certain accelerated trajectories.

• Oltean Marius [ pdf ]
  ‹ A frequency-domain implementation of the particle-without-particle approach to EMRIs ›
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  Marius Oltean University of Orleans & Autonomous University of Barcelona A frequency-domain implementation of the particle-without-particle approach to EMRIs The gravitational waves emitted by binary systems with extreme- or intermediate- mass ratios carry unique astrophysical information expected to be detected by the next generation of gravitational wave detectors. The detection of these binaries rely on an accurate modelling of the gravitational self-force that drives their orbital evolution. Although the theoretical formalism to compute the self-force has been fully developed, the mathematical tools needed to implement it are under development, and the self-force computation is still an open problem. The main obstacle is the singular nature of the gauge where the metric perturbations are usually computed, making the self-force calculation computationally challenging. We present here a frequency-domain implementation of the particle-without-particle (PwP) technique that was previously developed for the computation of the scalar self-force ? a helpful testbed for the gravitational self-force. We expect that this will yield significant improvements in computational time and hope that it will provide useful hints for circumventing the gauge singularity issues and ultimately computing the metric perturbations in the full gravitational case.

E) Cosmology and Gravitational Waves

• Conneely Ciarán [ pdf ]
  ‹ Gravitational Wave Backgrounds ›
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  Ciarán Conneely Imperial College London Gravitational Wave Backgrounds The direct detection of gravitational waves in 2015 by Advanced LIGO has started a new era of astronomy and it is assumed that there are sufficient sources to incoherently sum to an all-pervasive background that can be studied statistically. These waves have many properties that are analogous to photons – especially in terms of their polarisation. Both types of wave have two polarisations: “plus” and “cross” for gravitational waves and “vertical” and “horizontal” for photons. However, these are coordinate system dependent and so analysis of photon polarisation backgrounds (such as measurements of the CMB) is done in terms of coordinate independent “E” and “B” modes. In an almost mathematically identical way, a gravitational wave background can be considered in terms of similar modes. I will discuss the relative sensitivity of the proposed eLISA satellite detector to these modes and what can be learned about the backgrounds. For example, a pure stochastic background would lead to statistically identical E and B power spectra so a significant difference between the relative strengths of the two modes would imply there is something more complicated about the background, such as a preferred direction.

• Ghaffarnejad Hossein
  ‹ Weak Gravitational Lensing of quantum perturbed Lukewarm Black Holes and cosmological constant effect ›
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  Hossein Ghaffarnejad semnan university Weak Gravitational Lensing of quantum perturbed Lukewarm Black Holes and cosmological constant effect Aim of the paper is study weak gravitational lensing of quantum perturbed (QLBHL) and classical (CLBHL) Lukewarm black hole lens in presence of cosmological parameter $\Lambda$. We apply numerical method to evaluate deflection angle of bending light rays, Einstein rings $\beta=0,$ images locations of sample source $\beta=\frac{\pi}{4},$ and corresponding magnifications $\mu.$ Deflection angle takes positive (negative) values for CLBHL (QLBHL) and they decrease very fast (slow) by increasing closest distance $x_0$ of bending light ray and/or dimensionless cosmological parameter $\epsilon=\frac{16\Lambda M^2}{3}$. $M$ is ADM mass of the black hole lens. In case of CLBHL (QLBHL), the Einstein rings $\beta=0$ are formed for $\epsilon<0.52 (0.73<\epsilon<0.89)$ and images positions of the source $\beta=\frac{\pi}{4}$ are formed for $\epsilon<0.52 (0.18<\epsilon<0.89).$ Magnification of elementary images diverge to infinite value for $\epsilon_{critical}\approx0.35$ but not for secondary image.

• Guzzetti Maria Chiara [ pdf ]
  ‹ Constraining inflationary physics with primordial gravitational waves at small scales ›
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  Maria Chiara Guzzetti Università degli Studi di Padova - INFN Padova Constraining inflationary physics with primordial gravitational waves at small scales Any cosmological inflationary model predicts the production of a stochastic gravitational-wave (GW) background. Quantum fluctuations of the gravitational field underlying each inflationary model, originate such a signal. In addition, inflationary GW can be generated \textit{classically} due to the presence of a source provided, for example, by events of particle production or by the presence of the so-called spectator fields. Interestingly, single-field slow-roll inflation predicts a consistency relation involving GW, which links the tensor-to-scalar ratio and the GW spectral index by an equality. Quantum fluctuations of the gravitational field expected in modified gravity theories and the classical production of GW, can lead to the violation of such a consistency relation, conferring upon primordial GW a crucial role in discriminating among inflationary models. In particular, a blue GW power-spectrum, that is with an increasing amplitude on small scales, manifestly breaks the mentioned equality. Therefore, future GW detectors focused on small scales, such as eLISA, have the possibility of testing the consistency relation and of constraining the parameter space of several inflationary models. In the same direction, current bounds on the GW spectral energy-density spanning different scales will be presented, such as those provided by aLIGO and Planck experiments. (Based on arXiv:1605.01615)

• Khedidja Djeha
  ‹ Inflationary models and applications  ›
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  Djeha Khedidja Inflationary models and applications Study the cosmic microwave background: polarization and anisotropy. The inflationary model has been proposed to address the shortcomings of the standard model of cosmology. This cosmological model offer both a solution to the horizon problem and the flatness problem. The idea of inflation states that just after the Big Bang, the observable universe has experienced a violent expansion phase that would allow it to grow a significant factor. The collected data of the European satellite Planck reinforce the scenario of inflation. Launched in 2009, the satellite analyzed for 15 months the "cosmic microwave background: CMB". The analysis focused on the CMB temperature fluctuations. The theory of inflation also provides the polarization of this radiation. The satellite Planck was designed to also measure the polarization parameter. It is proposed in this poster to study the cosmic microwave background radiation, the anisotropy of its temperature and its polarization.

• Martinon Grégoire [ pdf ]
  ‹ Geons in anti-de Sitter spacetimes ›
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  Grégoire Martinon Observatoire de Paris Geons in anti-de Sitter spacetimes Geons are gravitational wave packets. They correspond to the original idea of J.A. Wheeler of a regular body with finite extension. In a geon, the GW don't escape to infinity because of their own gravitational potential that keep them together. These objects are manifestly unstable in asymptotically flat spacetimes and decay exponentially, but they do survive in asymptotically anti de-Sitter (AdS) spacetimes. The AdS spacetime, due to his negative curvature and his "reflective" boundary condition is unstable with respect to black hole perturbation : any small perturbation will collapse to a black hole after one or many bounces. Geons in AdS are an exception, they are non-linear GW packets that can reach arbitrarily high amplitudes and are a key element toward the understanding of the AdS stability. In this poster, I will introduce the basic properties of anti-de Sitter spacetime and explain what we currently understand about its instability. I will then describe the concept of geon in asymptotically anti-de Sitter spacetimes et show results of numerical simulations of such objects.

• Philippoz Lionel
  ‹ Detecting Additional Polarizations Modes with eLISA ›
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  Lionel Philippoz University of Zurich Detecting Additional Polarizations Modes with eLISA TBD

Contributed Sessions and Organizers

The following parallel sessions are foreseen. More will be announced as soon as available.

A) LISA Pathfinder - Results

Organizers:
Paul Mc Namara (ESA); Bill Weber (University of Trento); Martin Hewitson (Max Planck Institute for Gravitational Physics)

B) LISA Hardware

Organizers:
Oliver Jennrich (ESA); Gerhard Heinzel (Max Planck Institute for Gravitational Physics, Hannover)

C) Astrophysics with Gravitational Waves

Organizers:
Alberto Sesana (University of Birmingham); Monica Colpi (Università degli Studi di Milano-Bicocca); Gijs Nelemans (Radboud University)

D) Extreme Mass Ratio Inspirals (EMRI)

Organizers:
Carlos Sopuerta (Institute of Space Sciences CSIC-IEEC, Catalunya, Spain); Pau Amaro-Seoane (Albert Einstein Institute, Max Planck Institute for Gravitational Physics, Potsdam)

E) Cosmology and Gravitational Waves

Organizers:
Chiara Caprini (IPhT, CEA Saclay); Germano Nardini (Albert Einstein Center for Fundamental Physics, Universität Bern)

Conference Dinner

The conference dinner will take place on Wednesday evening, starting at 19:00 on the top of the Uetliberg.

How to get there by public transport

Go to Zurich, main station (Bahnhofplatz | HB) and take the SZU train S10 leaving from Track 22. (The conference ticket is valid, but please note that accompanying person need an additional ticket for 1-2 extra zone besides city zone.) The train takes about 20min to the final station, Uetliberg (1h from the conference).

How to get there by hikingt

The way up the hill is also a nice, but a little steep hike through the forest. Hiking shoes are not required.
Take the tram 14, bus 33 or train S10 to station Triemli and follow the signs upwards. The hike takes about 1 - 1.5 hours.