Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diffuse Gamma Rays from the Galactic Plane: Probing the "GeV Excess" and
  Identifying the "TeV Excess"   Pion decay gamma rays have long been recognized as a unique signature of
hadronic cosmic rays and their interactions with the interstellar medium. We
present a model-independent way of constraining this signal with observations
of the Galactic Plane in diffuse gamma rays. We combine detections by the EGRET
instrument at GeV energies and the Milagro Cherenkov detector at TeV energies
with upper limits from KASCADE and CASA-MIA ground arrays at PeV energies. Such
a long "lever arm", spanning at least six orders of magnitude in energy,
reveals a "TeV excess" in the diffuse Galactic Plane gamma-ray spectrum. While
the origin of this excess is unknown, it likely implies also enhanced TeV
neutrino fluxes, significantly improving the prospects for their detection. We
show that unresolved point sources are a possible source of the TeV excess. In
fact, the spectra of the unidentified EGRET sources in the Milagro region must
break between ~10 GeV and ~1 TeV to avoid strongly overshooting the Milagro
measurement; this may have important implications for cosmic-ray acceleration.
  Finally, we use our approach to examine the recent suggestion that
dark-matter annihilation may account for the observed excess in diffuse
Galactic gamma-rays detected by EGRET at energies above 1 GeV. Within our
model-independent approach, current data cannot rule this possibility in or
out; however we point out how a long "lever arm" can be used to constrain the
pionic gamma-ray component and in turn limit the "GeV excess" and its possible
sources. Experiments such as HESS and MAGIC, and the upcoming VERITAS and
GLAST, should be able to finally disentangle the main sources of the Galactic
gamma rays.

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The categories of this paper are: math
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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: econ
34
The categories of this paper are: chem-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: cs
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The categories of this paper are: nucl-ex