Excess of EGRET Galactic Gamma Ray Data interpreted as Dark Matter Annihilation

TL;DR

The paper interprets the excess gamma ray data from EGRET as a potential signal of Dark Matter annihilation, constraining WIMP mass, halo structure, and supporting the supersymmetric dark matter hypothesis with high statistical significance.

Contribution

It provides a detailed analysis linking gamma ray excess to Dark Matter annihilation, constraining WIMP mass, halo shape, and correlating with galactic structures, which is a novel comprehensive interpretation.

Findings

Gamma ray excess consistent with Dark Matter annihilation spectrum

Halo structure is a triaxial isothermal profile with a DM ring at 14 kpc

Supports supersymmetric dark matter models with boost factors above 20

Abstract

The diffuse galactic EGRET gamma ray data show a clear excess for energies above 1 GeV in comparison with the expectations from conventional galactic models. The excess is seen with the same spectrum in all sky directions, as expected for Dark Matter (DM) annihilation. This hypothesis is investigated in detail. The energy spectrum of the excess is used to limit the WIMP mass to the 50-100 GeV range, while the sky maps are used to determine the halo structure, which is consistent with a triaxial isothermal halo with additional enhancement of Dark Matter in the disc. The latter is strongly correlated with the ring of stars around our galaxy at a distance of 14 kpc, thought to originate from the tidal disruption of a dwarf galaxy. It is shown that this ring of DM with a mass of $\approx 2\cdot 10^{11} M_\odot$ causes the mysterious change of slope in the rotation curve at $R=1.1R_0$ and the large local surface density of the disc. The total mass of the halo is determined to be $3\cdot 10^{12} M_\odot$. A cuspy profile is definitely excluded to describe the gamma ray data. These signals of Dark Matter Annihilation are compatible with Supersymmetry for boost factors of 20 upwards and have a statistical significance of more than $10\sigma$ in comparison with the conventional galactic model. The latter combined with all features mentioned above provides an intriguing hint that the EGRET excess is indeed a signal from Dark Matter Annihilation.