Bounds on Dark Matter Annihilations from 21-cm data

Tuesday, 02 October 2018 at 11:15, in Y16 G05 - Campus Irchel

In March 2018 the EDGES experiment has reported the discovery of an absorption feature in the 21-cm spectrum at redshift around 17. This measurement, if confirmed, is fundamental because can give us information about the epoch of reionization soon after the formation of first stars and galaxies. This talk is organised in three parts. In the first part I’ll present the EDGES experiment and the procedure the collaboration has used to extract the broad absorption profile from the strong galactic synchrotron emission. Then I’ll review the physics of the 21-cm line and the history of the InterGalactic Medium (IGM) properties assuming a LambdaCDM Universe. Finally, I’ll conclude with a simple application of this measurement to set bounds on the Dark Matter (DM) properties. In particular, annihilating DM particles produce significant heating of the IGM erasing the absorption feature measured by EDGES. These limits, derived for the first time in our paper, are comparable to the strongest ones from all other observables.