Gamma-Ray Emissions from Dark Matter?

April 10, 2014

Past studies have identifed a spatially extended excess of 1-3 GeV gamma rays from the region surrounding the Galactic Center, consistent with the emission expected from annihilating dark matter.  Harvard Physics grad student Tansu Daylan, Prof. Douglas Finkbeiner, and researchers from Fermilab, University of Chicago,  MIT, and Princeton revisited and scrutinized this signal with the intention of further constraining its characteristics and origin. By applying cuts to the Fermi event parameter CTBCORE, the scientists suppressed the tails of the point spread function and generated high resolution gamma-ray maps, enabling them to more easily separate the various gamma-ray components. Within these maps, the GeV excess was found to be robust and highly statistically significant, with a spectrum, angular distribution, and overall normalization that is in good agreement with that predicted by simple annihilating dark matter models. Furthermore, the scientists confirmed that the angular distribution of the excess is approximately spherically symmetric and centered around the dynamical center of the Milky Way (within ~0.05 of Sgr A*), showing no sign of elongation along or perpendicular to the Galactic Plane. The signal is observed to extend to at least ⋍10 from the Galactic Center, disfavoring the possibility that this emission originates from millisecond pulsars.

See Tansu Daylan, Douglas P. Finkbeiner, Dan Hooper, Tim Linden, Stephen K. N. Portillo, Nicholas L. Rodd, Tracy R. Slatyer, "The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Compelling Case for Annihilating Dark Matter," arXiv:1402.6703.  Also read the CfA Press Release.