A tentative gamma-ray line from Dark Matter annihilation at the Fermi Large Area Telescope

作者：Weniger Christoph^*

来源：Journal of Cosmology and Astroparticle Physics, 2012, (8): 007.

DOI：10.1088/1475-7516/2012/08/007

• dark matter experiments
• gamma ray experiments
• dark matter theory

The observation of a gamma-ray line the cosmic-ray fluxes would he a smoking-gun signature for dark matter annihilation or decay in the Universe. We present an improved search for such signatures in the data of the Fermi Large Area Telescope (LAT), concentrating on energies between 20 and 300 GeV. Besides updating to 43 months of data, we use a new data-driven technique to select optimized target regions depending on the profile of the Galactic dark matter halo. In regions close to the Galactic center, we find a 4.6 sigma indication for a gamma-ray line at E-gamma approximate to GeV. When taking into account the look-elsewhere effect the significance of the observed excess is 3.20 sigma. If interpreted in terms of dark matter particles annihilating into a photon pair, the observations imply a dark matter mass of m(chi) = 129.8 +/- 2.4(-1.3)(+7) GeV and a partial annihilation cross-section of (chi chi ->gamma gamma) = (1.27 +/- 0.32(-028)(+0.18)) x 10(-2)7 cm(3) s(-1) when using the Einasto dark matter profile. The evidence for the signal is based on about 50 photons; it will take a few years of additional data to clarify its existence.

• 出版日期2012-8