Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dark Matter Annihilation in The Galactic Center As Seen by the Fermi
  Gamma Ray Space Telescope   We analyze the first two years of data from the Fermi Gamma Ray Space
Telescope from the direction of the inner 10 degrees around the Galactic Center
with the intention of constraining, or finding evidence of, annihilating dark
matter. We find that the morphology and spectrum of the emission between 1.25
degrees and 10 degrees from the Galactic Center is well described by a the
processes of decaying pions produced in cosmic ray collisions with gas, and the
inverse Compton scattering of cosmic ray electrons in both the disk and bulge
of the Inner Galaxy, along with gamma rays from known points sources in the
region. The observed spectrum and morphology of the emission within
approximately 1.25 degrees (~175 parsecs) of the Galactic Center, in contrast,
departs from the expectations for by these processes. Instead, we find an
additional component of gamma ray emission that is highly concentrated around
the Galactic Center. The observed morphology of this component is consistent
with that predicted from annihilating dark matter with a cusped (and possibly
adiabatically contracted) halo distribution (density proportional to
r^{-gamma}, with gamma=1.18 to 1.33). The observed spectrum of this component,
which peaks at energies between 1-4 GeV (in E^2 units), can be well fit by a
7-10 GeV dark matter particle annihilating primarily to tau leptons with a
cross section in the range of 4.6 x 10^-27 to 5.3 x 10^-26 cm^3/s, depending on
how the dark matter distribution is normalized. We also discuss other sources
for this emission, including the possibility that much of it originates from
the Milky Way's supermassive black hole.

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The categories of this paper are: nucl-th
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The categories of this paper are: hep-th
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The categories of this paper are: quant-ph
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The categories of this paper are: stat
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The categories of this paper are: gr-qc
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The categories of this paper are: supr-con
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
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The categories of this paper are: physics
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: nlin
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The categories of this paper are: math