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HEP Seminar: Disrupted Globular Clusters as the Source of the Galactic Center GeV Excess

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Timothy Brandt, Institute for Advanced Study
When
22 February 2017 from 2:30 PM to 3:30 PM
Where
339 Davey Laboratory
Contact Name
Kohta Murase
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The Fermi satellite has recently detected excess gamma ray emission from the central regions of our Galaxy.  This may be evidence for dark matter particles, a major component of the standard cosmological model, annihilating to produce high-energy photons.  I will show that the observed signal may instead be generated by millisecond pulsars that formed in dense globular clusters in the Galactic halo.  Most of these clusters were ultimately disrupted by evaporation and gravitational tides, contributing to a spherical bulge of stars and stellar remnants. The gamma ray amplitude, angular distribution, and spectral signatures of this source may be predicted without free parameters, and are in remarkable agreement with the observations. The gamma rays are then from the fossil remains of dispersed clusters, and constitute the first direct evidence for the former existence of a much larger globular cluster population.

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