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Title: Lining up the Galactic Center gamma-ray excess

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of the Dark Universe
Additional Journal Information:
Journal Volume: 7-8; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-03 22:31:54; Journal ID: ISSN 2212-6864
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Citation Formats

McDermott, Samuel D. Lining up the Galactic Center gamma-ray excess. Netherlands: N. p., 2015. Web. doi:10.1016/j.dark.2015.05.001.
McDermott, Samuel D. Lining up the Galactic Center gamma-ray excess. Netherlands. doi:10.1016/j.dark.2015.05.001.
McDermott, Samuel D. 2015. "Lining up the Galactic Center gamma-ray excess". Netherlands. doi:10.1016/j.dark.2015.05.001.
title = {Lining up the Galactic Center gamma-ray excess},
author = {McDermott, Samuel D.},
abstractNote = {},
doi = {10.1016/j.dark.2015.05.001},
journal = {Physics of the Dark Universe},
number = C,
volume = 7-8,
place = {Netherlands},
year = 2015,
month = 3

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.dark.2015.05.001

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Cited by: 12works
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  • Several groups have recently claimed evidence for an unaccounted gamma-ray excess over the diffuse backgrounds at few GeV in the Fermi-LAT data in a region around the Galactic Center, consistent with a dark matter annihilation origin. We demonstrate that the main spectral and angular features of this excess can be reproduced if they are mostly due to inverse Compton emission from high-energy electrons injected in a burst event of ∼ 10{sup 52}÷10{sup 53} erg roughly O(10{sup 6}) years ago. We consider this example as a proof of principle that time-dependent phenomena need to be understood and accounted for—together with detailed diffuse foregrounds andmore » unaccounted ''steady state'' astrophysical sources—before any robust inference can be made about dark matter signals at the Galactic Center. In addition, we point out that the timescale suggested by our study, which controls both the energy cutoff and the angular extension of the signal, intriguingly matches (together with the energy budget) what is indirectly inferred by other evidences suggesting a very active Galactic Center in the past, for instance related to intense star formation and accretion phenomena.« less
  • Recent analyses of Fermi Large Area Telescope data show an extended GeV γ-ray excess on top of the expected diffuse background in the Galactic center region, which can be explained by annihilating dark matter (DM) or a population of millisecond pulsars (MSPs). We propose observations of very high energy (VHE) γ-rays to distinguish the MSP scenario from the DM scenario. GeV γ-ray MSPs should release most of their energy to the relativistic e{sup ±} wind, which will diffuse into the Galaxy and radiate TeV γ-rays through inverse Compton scattering and bremsstrahlung processes. By calculating the spectrum and spatial distribution, wemore » show that such emission is detectable with the next generation VHE γ-ray observatory, the Cherenkov Telescope Array (CTA), under reasonable model parameters. It is essential to search for multi-wavelength counterparts to the GeV γ-ray excess in order to solve this mystery in the high-energy universe.« less
  • Motivated by the gamma-ray excess observed from the region surrounding the Galactic Center, we explore particle dark matter models that could potentially account for the spectrum and normalization of this signal. Taking a model-independent approach, we consider an exhaustive list of tree-level diagrams for dark matter annihilation, and determine which could account for the observed gamma-ray emission while simultaneously predicting a thermal relic abundance equal to the measured cosmological dark matter density. We identify a wide variety of models that can meet these criteria without conflicting with existing constraints from direct detection experiments or the Large Hadron Collider (LHC). Themore » prospects for detection in near future dark matter experiments and/or the upcoming 14 TeV LHC appear quite promising.« less
  • Thermal relic dark matter particles with a mass of 31-40 GeV and that dominantly annihilate to bottom quarks have been shown to provide an excellent description of the excess gamma rays observed from the center of the Milky Way. Flavored dark matter provides a well-motivated framework in which the dark matter can dominantly couple to bottom quarks in a flavor-safe manner. We propose a phenomenologically viable model of bottom flavored dark matter that can account for the spectral shape and normalization of the gamma-ray excess while naturally suppressing the elastic scattering cross sections probed by direct detection experiments. This modelmore » will be definitively tested with increased exposure at LUX and with data from the upcoming high-energy run of the Large Hadron Collider (LHC).« less