Dark matter, extra-terrestrial gamma-rays and the MSSM: a viability study

Abstract

We fit the $\gamma$-ray excess from the galactic centre (GC) in terms of parameters of the minimal supersymmetric standard model (MSSM). Consistency with other $\gamma$-ray observation, such as those from dwarf spheroidal galaxies, is also ensured, in addition to the constraints from direct dark matter search. Furthermore, we expect the contribution to the relic density from the MSSM dark mater candidate, namely, the lightest neutralino, should not go below the stipulated value; otherwise it will amount to going beyond the MSSM by including some additional dark matter source. After a detailed scan of the parameter space in terms of four representative types of particle spectra, we identify the ones that are best fit to the observed data. However, these two are somewhat unsatisfactory in terms of $\chi^2_{min}$ as well as $p$-values. In some case(s), the unacceptability of low-$\chi^2_{min}$ regions due to direct search constraint is responsible for this. In others, the observed shape of the $\gamma$-ray spectrum makes the fits unsatisfactory. The imposed lower limit on relic density, too, has a role to play all along. On the whole, the conclusion is that the MSSM is not a very satisfactory fit for the GC $\gamma$-ray compounded with other cosmological observations and direct search limits.