CLUES on Fermi-LAT prospects for the extragalactic detection of μνSSM gravitino dark matter

Abstract

The µνSSM is a supersymmetric model that has been proposed to solve the problems generated by other supersymmetric extensions of the standard model of particle physics. Given that R-parity is broken in the µνSSM, the gravitino is a natural candidate for decaying dark matter since its lifetime becomes much longer than the age of the Universe. In this model, gravitino dark matter could be detectable through the emission of a monochromatic gamma ray in a two-body decay. We study the prospects of the Fermi-LAT telescope to detect such monochromatic lines in 5 years of observations of the most massive nearby extragalactic objects. The dark matter halo around the Virgo galaxy cluster is selected as a reference case, since it is associated to a particularly high signalto-noise ratio and is located in a region scarcely affected by the astrophysical diffuse emission from the galactic plane. The simulation of both signal and background gamma-ray events is carried out with the Fermi Science Tools, and the dark matter distribution around Virgo is taken from a N -body simulation of the nearby extragalactic Universe, with constrained initial conditions provided by the CLUES project. We find that a gravitino with a mass range of 0.6-2 GeV, and with a lifetime range of about 3 × 10 27 -2 × 10 28 s would be detectable by the Fermi-LAT with a signal-to-noise ratio larger than 3. We also obtain that gravitino masses larger than about 4 GeV are already excluded in the µνSSM by Fermi-LAT data of the galactic halo.

Constraining light dark matter with diffuse X-ray and gamma-ray observations

“…The available data cover a photon energy range from 10's of GeV down to a few keV, providing the possibility of exploring a much broader range of DM candidates than WIMPs. Indeed, some of these data have already been utilized to constrain LDM, see, e.g., [33][34][35][36][37][38][39][40][41][42][43][44]. Sterile neutrinos with a mass ∼ O(1 − 10 keV) are a particularly popular candidate and their constraints have been explored in, e.g., [36, 38-40, 45-51, 51-57].…”

Probing neutrino physics at LHC throughR-parity breaking supersymmetry

“…Other analyses concerning cosmology such as gravitino dark matter and electroweak baryogenesis can be found in Refs. [37,38] and in Ref. [39], respectively.…”

“…If the RPV parameter |Uγ ν | from the 7 × 7 neutralino mixing matrix is between 10 −16 and 10 −12 , the correct neutrino masses are reproduced. Values of the gravitino mass larger than 10 GeV are disfavoured, as well as lifetimes smaller than about 3 to 5 × 10 27 s. Further studies on the prospects of the Fermi-LAT telescope to detect such monochromatic lines in five years of observations of the most massive nearby extragalactic objects have been performed [38]. It was found that a gravitino with a mass range of 0.6 − 2 GeV, and with a lifetime range of about 3 × 10 27 − 2 × 10 28 s would be detectable by the Fermi-LAT with a signal-to-noise ratio larger than 3. it has also been shown that gravitino masses larger than about 4 GeV are already excluded in the μνSSM by Fermi-LAT data of the galactic halo [37].…”

Searching for SUSY and decaying gravitino dark matter at the LHC and Fermi-LAT with the $\mu\nu$SSM

“…The detection of gravitino DM in several RPV scenarios has been studied in the literature considering the case of gravitinos emitting gamma rays when decaying in the smooth galactic halo and extragalactic regions at cosmological distances [18,21,19,22,23], and also in nearby extragalactic structures [24]. In the interesting case of the galactic halo, the gamma-ray signal is an anisotropic sharp line and the flux is given by…”