Gamma-rays from nearby clusters: Constraints on selected decaying dark matter models

Abstract

Recently, the Fermi-LAT collaboration reported upper limits on the GeV gamma-ray flux from nearby clusters of galaxies. Motivated by these limits, we study corresponding constraints on gamma-ray emissions from two specific decaying dark matter models, one via grand unification scale suppressed operators and the other via R-parity violating operators. Both can account for the PAMELA and Fermi-LAT excesses of e ± . For GUT decaying dark matter, the gamma-rays from the M49 and Fornax clusters, with energy in the range of 1 to 10 GeV, lead to the most stringent constraints to date. As a result, this dark matter is disfavored with conventional model of e ± background. In addition, it is likely that some tension exists between the Fermi-LAT e ± excess and the gamma-ray constraints for any decaying dark matter model, provided conventional model of e ± background is adopted. Nevertheless, the GUT decaying dark matter can still solely account for the PAMELA positron fraction excess without violating the gamma-ray constraints.For the gravitino dark matter model with R-parity violation, cluster observations do not give tight constraints. This is because a different e ± background has been adopted which leads to relatively light dark matter mass around 200 GeV. *

Indirect Searches for Decaying Dark Matter

“…References 129 and 138 searched for such emission in up to eight clusters using Fermi LAT data (see also Refs. 123,135,[151][152][153][154]. No signal was found, and upper limits were derived on the decay rate by merging the likelihood functions of the different observations into a combined likelihood that also takes into account cluster mass uncertainties associated with the underlying X-ray measurements.…”

Gamma ray constraints on flavor violating asymmetric dark matter

“…The case of lepton-flavor preserving primary channels (i.e. i = j) has been studied in [30][31][32][33][34][35][36][37]. An improved analysis appeared recently in [31] making use of the electroweak corrections for the primary fluxes of the relevant stable standard model particles determined in [38,40] and a refinement of the propagation scheme for the e ± (see [38] for further details).…”

Publisher’s Note: Gamma Ray Constraints on Decaying Dark Matter [Phys. Rev. D86, 083506 (2012)]

“…This impacts both the analysis of the e AE fits (mildly) and the fluxes of inverse Compton scattering gamma rays from the galactic halo (more significantly). Some recent studies have performed work related to ours [14,15,[27][28][29][30][31][32][33]. The most closely related, as far as the isotropic gamma ray flux is concerned, is Ref.…”