Lyman-α constraints on cosmic heating from dark matter annihilation and decay

We derive new constraints on models of decaying and annihilating dark matter (DM) by requiring that the energy injected into the intergalactic medium (IGM) not overheat it at late times, when measurements of the Lyman-a forest constrain the IGM temperature. We improve upon previous analyses by using the recently developed DarkHistory code package, which self-consistently takes into account additional photoionization and photoheating processes due to reionization and DM sources. Our constraints are robust to the uncertainties of reionization and competitive with leading limits on sub-GeV DM that decays preferentially to electrons [https://github.com/hongwanliu/DarkHistory/treeff_igm_temperature_constraints].

Automated summary

We have derived new constraints on models of decaying and annihilating dark matter by ensuring that the energy injected into the intergalactic medium does not overheat it at late times. These constraints, obtained using the DarkHistory code package, are robust to uncertainties in reionization and competitive with other limits on dark matter.