Putting all the X in one basket: Updated X-ray constraints on sub-GeV Dark Matter

Abstract

Sub-GeV dark matter particles can annihilate or decay producing e ^± pairs which upscatter the low-energy photon fields in the Galaxy and generate an X-ray emission (via the Inverse Compton effect). Using X-ray data from XMM-NEWTON, INTEGRAL, NUSTAR and SUZAKU, we derive new constraints on this class of dark matter (DM). In the annihilation case, our new bounds are the strongest available for DM masses above 180 MeV, reaching <σv> ≲ 10^-28 cm³/s for m _DM ≃ 1 GeV. In the decay case, our bounds are the strongest to date over a large fraction of the considered mass range, constraining τ ≳ 10²⁸ s for m _DM ≃ 1 GeV and improving by up to 3 orders of magnitude upon existing limits.