Vivian Poulin (JHU) "Shedding Light on Dark Matter with the CMB: Implications for EDGES 21cm Signal"

In this talk, I would like to review how the Cosmic Microwave Background (in particular its temperature and polarization anisotropies) can be used to perform both direct and indirect detection of Dark Matter.  In a first part, I will show how the CMB can be used to put stringent constraints on DM models leading to energy injection, such as DM annihilations and decay or Primordial Black Holes matter accretion. I will compare CMB bounds to those coming from galactic cosmic and gamma ray searches and illustrate how the 21cm signal, a major target of next generation surveys, can be used to significantly improve over current limits. In a second part, I will discuss a recent puzzling absorption feature in the global 21cm signal observed by the EDGES experiment. Such feature could be explained by efficient scattering between DM and baryons in the late universe. I will show how the CMB strongly challenges such explanation of that signal.