Gravitino Dark Matter

TL;DR

This paper explores gravitino dark matter, its implications for superparticle masses, and potential observable signatures in cosmic rays and gamma-ray spectra, highlighting the constraints and astrophysical sources involved.

Contribution

It analyzes the decay signatures of gravitino dark matter and their compatibility with cosmic ray and gamma-ray observations, considering R-parity breaking effects.

Findings

Decaying gravitinos cannot fully explain PAMELA and Fermi LAT fluxes.

Gamma-ray line signatures below 300 GeV are possible from gravitino decay.

Constraints on superparticle masses are derived from cosmological and astrophysical data.

Abstract

Gravitino dark matter, together with thermal leptogenesis, implies an upper bound on the masses of superparticles. In the case of broken R-parity the constraints from primordial nucleosynthesis are naturally satisfied and decaying gravitinos lead to characteristic signatures in high energy cosmic rays. Electron and positron fluxes from gravitino decays cannot explain both, the PAMELA positron fraction and the electron + positron flux recently measured by Fermi LAT. The observed fluxes require astrophysical sources. The measured antiproton flux allows for a sizable contribution of decaying gravitinos to the gamma-ray spectrum, in particular a line at an energy below 300 GeV.