Evidence for Dark Matter Annihilation from Galactic Gamma Rays?

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 skymaps 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 indirect evidence for Dark Matter Annihilation.

To be published in Proc. of DM 2004, Feb. 2004, Los Angeles; updated references and somewhat improved fits in new version

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Cited by in corpus (17)

• Pre-launch estimates for GLAST sensitivity to Dark Matter annihilation signals
• The Besancon Galaxy model renewed I. Constraints on the local star formation history from Tycho data
• The fine-grained phase-space structure of Cold Dark Matter halos
• EGRET Excess of Diffuse Galactic Gamma Rays as Tracer of Dark Matter
• Vertical distribution of Galactic disk stars: III. The Galactic disk surface mass density from red clump giants
• Is the dark matter interpretation of the EGRET gamma excess compatible with antiproton measurements?
• Adiabatic compression and indirect detection of supersymmetric dark matter
• EGRET Excess of diffuse Galactic Gamma Rays interpreted as a Signal of Dark Matter Annihilation
• Dark Matter Search Experiments
• Galactic diffuse gamma rays --- recalculation based on the new measurements of cosmic electron spectrum
• WIMP annihilation in caustics
• The diffuse GeV-TeV $\gamma$-ray emission of the Cygnus region
• Cross-Correlation analysis of WMAP and EGRET in Wavelet Space
• Numerical Simulations of the Dark Universe: State of the Art and the Next Decade
• Indirect Evidence for WIMP Annihilation from Diffuse Galactic Gamma Rays
• Ultra High Energy Cosmic Rays from decays of Holeums in Galactic Halos
• Perspective of Galactic dark matter subhalo detection on Fermi from the EGRET observation