New AMS-02 positron fraction and Fermi-LAT Extragalactic Gamma-Ray Background measurements vs. gravitino dark matter
Germán A. Gómez-Vargas (PUC-Chile)
Roberto A. Lineros (IFIC UVEG-CSIC)
The positron fraction measured by PAMELA, Fermi-LAT and AMS-02 presents anomalous behaviour as energy increase. The origin of the source responsible for this is still unknown, it can be non-exotic (e.g. pulsars), be dark matter (DM) or maybe a mixture. We test the gravitino of bilinear R-parity violating supersymmetric (SUSY) models as this source. With a nobel fitting procedure we find that we can account for the positron rise using a gravitino dark matter with mass in the range 1-2 TeV and lifetime of ~ 1.0 – 0.8 x 10^26 s. The corresponding gamma-ray flux is in conflict with the most recent determination of the Extragalactic Gamma-ray Background (EGB) with the Fermi-LAT, excluding the gravitino DM as the unique source of primary positrons. Thus, if gravitinos of bilinear R-parity violating SUSY models made up the whole DM of the Universe, they can only produce a modest fraction of the highest energetic electron and positron fluxes detected at the Earth.