Gamma Ray Spectrum from Gravitino Dark Matter Decay

TL;DR

This paper calculates the gamma ray spectrum resulting from gravitino dark matter decay, which could be detected by future gamma-ray observatories, providing a potential signature of supersymmetric dark matter.

Contribution

It presents the first detailed computation of the photon energy spectrum from gravitino decay with R-parity violation, highlighting its distinctive features for future detection.

Findings

Photon spectrum has a characteristic shape with a potential monochromatic line.

Decay lifetime exceeds the age of the Universe, consistent with dark matter constraints.

Provides predictions for gamma-ray signals detectable by upcoming experiments.

Abstract

Gravitinos are very promising candidates for the cold dark matter of the Universe. Interestingly, to achieve a sufficiently long gravitino lifetime, R-parity conservation is not required, thus preventing any dangerous cosmological influence of the next-to-lightest supersymmetric particle. When R-parity is violated, gravitinos decay into photons and other particles with a lifetime much longer than the age of the Universe, producing a diffuse gamma ray flux with a characteristic spectrum that could be measured in future experiments, like GLAST or AMS-02. In this letter we compute the energy spectrum of photons from gravitino decay and discuss its main qualitative features.