Forbidden Dark Matter Combusted Around Supermassive Black Hole

TL;DR

This paper explores how forbidden dark matter can be reactivated near supermassive black holes, leading to potential gamma-ray signals detectable by telescopes like Fermi-LAT, offering a new way to identify dark matter.

Contribution

It introduces the concept of reactivating forbidden dark matter annihilation around black holes, providing a novel mechanism and potential observational signatures.

Findings

Reactivation of forbidden dark matter annihilation near black holes is possible.

Fermi-LAT data constrains the annihilation cross section consistent with relic density.

Unique gamma-ray signals could serve as evidence for forbidden dark matter.

Abstract

The forbidden dark matter cannot annihilate into a pair of heavier partners, either SM particles or its partners in the dark sector, at the late stage of cosmological evolution by definition. We point out the possibility of reactivating the forbidden annihilation channel around supermassive black holes. Being attracted towards a black hole, the forbidden dark matter is significantly accelerated to overcome the annihilation threshold. The subsequent decay of the annihilation products to photon leaves a unique signal around the black hole, which can serve as a smoking gun for the forbidden dark matter. For illustration, the Fermi-LAT data around Sgr $A^*$ provides a preliminary constraint on the thermally averaged cross section of the reactivated forbidden annihilation that is consistent with the DM relic density requirement.