Annihilation of singlet fermionic dark matter into two photons via pseudo-scalar mediator

Abstract

Abstract We consider the indirect detection of dark matter within an extension of the standard model (SM) including a singlet fermion as cold dark matter (CDM) and a singlet pseudo-scalar as a mediator between dark matter and the SM particles. The annihilation cross-section of the CDM into two monochromatic photons is calculated and compared with the latest H.E.S.S. data. Although for dark matter masses below 1 TeV the predicted observable cross-sections are far from the sensitivity of the recent gamma-ray experiments, it can be comparable to the strongest H.E.S.S. upper bounds for some models with more massive CDM.