Secular Café: Evidence of Dark Matter? 130-GeV gamma rays from near our galaxy's core

Secular Café Serious discussion of science, skepticism, evolution, pseudoscience, and the paranormal

Evidence of Dark Matter? 130-GeV gamma rays from near our galaxy's core May 27th 2012, 20:32 The Reference Frame: A confirmation of the 130 GeV dark matter-like bump - Lubos Motl [1204.2797] A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope - Christoph Weniger Quote: The observation of a gamma-ray line in the cosmic-ray fluxes would be 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 130 GeV. When taking into account the look-elsewhere effect the significance of the observed excess is 3.3 sigma. If interpreted in terms of dark matter particles annihilating into a photon pair, the observations imply a dark matter mass of 129.8\pm2.4^{+7}_{-13} GeV and a partial annihilation cross-section of <\sigma v> = 1.27\pm0.32^{+0.18}_{-0.28} x 10^-27 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. [1205.1045] Fermi 130 GeV gamma-ray excess and dark matter annihilation in sub-haloes and in the Galactic centre - Elmo Tempel, Andi Hektor, Martti Raidal Quote: We analyze publicly available Fermi-LAT high-energy gamma-ray data and confirm the existence of clear spectral feature peaked at $E_\gamma= 130$ GeV. Scanning over the Galaxy we identify several disconnected regions where the observed excess originates from. Our best optimized fit is obtained for the central region of Galaxy with a clear peak at 130 GeV with statistical significance $4.5\sigma.$ The observed excess is not correlated with Fermi bubbles. We compute the photon spectra induced by dark matter annihilations into two and four standard model particles, the latter via two light intermediate states, and fit the spectra with data. Since our fits indicate sharper and higher signal peak than in the previous works, data disfavors all but the dark matter direct two-body annihilation channels into photons. If Einasto halo profile correctly predicts the central cusp of Galaxy, dark matter annihilation cross-section to two photons is of order ten percent of the standard thermal freeze-out cross-section. If the observed gamma-ray excess comes from dark matter annihilations, we have identified the most dense dark matter sub-structures of our Galaxy. The large dark matter two-body annihilation cross-section to photons may signal a new resonance that should be searched for at the CERN LHC experiments. Almost but not quite 5 standard deviations, but if this result holds up, it will be indirect evidence of dark matter: DM particles running into each other and making other particles as they cancel each other out. The same effect has been observed for electrons and positrons: they go into orbit around each other, then radiate usually 2 or 3 gamma rays as they run into each other. The all-sky distribution of 511 keV electron-positron annihilation emission

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