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Résumé |
In March 2018 the EDGES experiment has reported the discovery of a 21-cm signal
in absorption between redshift 20 and 15. This measurement, if confirmed, is
fundamental for astrophysics because it 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 will present the EDGES
experiment and the procedure the collaboration has used to extract the broad
absorption profile from strong foreground of galactic synchrotron emission.
Then I will review the physics of the 21-cm signal and the history of the
InterGalactic Medium (IGM) properties assuming a LambdaCDM Universe. Finally, I
will 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 new limits on the annihilation cross section into standard
model particles are comparable to the strongest ones from all other
observables. |
