Effect of Degenerate Particles on Internal Bremsstrahlung of Majorana Dark Matter

TL;DR

This paper explores how degenerate particles can enhance the internal bremsstrahlung signal of Majorana dark matter, making it detectable by future gamma-ray experiments without conflicting with relic density constraints.

Contribution

It introduces degenerate particles with Majorana dark matter to significantly boost the internal bremsstrahlung cross section, enabling potential detection by upcoming gamma-ray telescopes.

Findings

Cross section enhancement of about one order of magnitude.

Potential detectability by GAMMA-400 and CTA.

Compatibility with relic density and other constraints.

Abstract

Gamma-rays induced by annihilation or decay of dark matter can be its smoking gun signature. In particular, gamma-rays generated by internal bremsstrahlung of Majorana and real scalar dark matter is promising since it can be a leading emission of sharp gamma-rays. However in the case of Majorana dark matter, its cross section for internal bremsstrahlung cannot be large enough to be observed by future gamma-ray experiments if the observed relic density is assumed to be thermally produced. In this paper, we introduce some degenerate particles with Majorana dark matter, and show they lead enhancement of the cross section. As a result, increase of about one order of magnitude for the cross section is possible without conflict with the observed relic density, and it would be tested by the future gamma-ray experiments such as GAMMA-400 and Cherenkov Telescope Array (CTA). In addition, the constraints of perturbativity, positron observation by the AMS experiment and direct search for dark matter are discussed.