[HET seminar] A new path for dark matter searches: cross-correlation between gamma rays and neutral hydrogen

by Elena Pinetti (Fermilab)

Thursday 14 Apr 2022, 11:00 → 12:30 US/Eastern

https://bnl.zoomgov.com/j/1612154637?pwd=Z2E5RWhqRXBkMnExQzc3eVBTWTg3UT09

Dark matter in cosmic structures is expected to produce signals originated from its particle physics nature, among which the electromagnetic emission represents a relevant opportunity, whose intensity is directly linked to the amount of dark matter in galaxies and clusters. On the other hand, this emission is very faint, thus contributing only at the unresolved level. These unresolved radiation backgrounds are isotropic at first order, but must exhibit a degree of anisotropy since they originate from clustered dark matter haloes. This fact implies also that the anisotropies in the radiation fields should be correlated to the same matter distribution in the Universe.
In this talk we propose to exploit this correlation by using the intensity mapping of the 21cm emission line of neutral hydrogen as the tracer of matter distribution, and gamma rays as the tracer of particle dark matter annihilation. Intensity mapping has the advantage of not being flux limited in the measurement of the matter distribution (as instead galaxy catalogs are) since it does not need to identify individual galaxies, and offers excellent redshift information being a line emission. We show the expected level for this cross-correlation signal and we derive forecasts for the study of this novel signature through the combination of Fermi-LAT gamma rays data and SKA intensity mapping capabilities.