The cosmic X-ray and gamma-ray background from dark matter annihilation

Jes̼s Zavala Franco

March 21, 2011

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Abstract: The extragalactic background radiation (EBR) observed at multiple wavelengths is a promising tool to probe the nature of dark matter. This radiation might contain a significant contribution from gamma-rays produced promptly by dark matter annihilation in the many halos and subhalos within our past light cone. Additionally, the electrons and positrons produced in the annihilation give energy to the cosmic microwave photons to populate the EBR with X-rays and gamma-rays. To study these signals, we create full-sky maps of the expected radiation from both of these contributions using the high-resolution Millennium-II simulation of cosmic structure formation. We show how observational upper limits on the contributions of unknown sources to the EBR can be used to constraint the intrinsic properties of dark matter.