Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Galactic Center GeV Excess from a Series of Leptonic Cosmic-Ray
  Outbursts   It has been proposed that a recent outburst of cosmic-ray electrons could
account for the excess of GeV-scale gamma rays observed from the region
surrounding the Galactic Center. After studying this possibility in some
detail, we identify scenarios in which a series of leptonic cosmic-ray
outbursts could plausibly generate the observed excess. The morphology of the
emission observed outside of $\sim1^{\circ}-2^{\circ}$ from the Galactic Center
can be accommodated with two outbursts, one which took place approximately
$\sim10^6$ years ago, and another (injecting only about 10\% as much energy as
the first) about $\sim10^5$ years ago. The emission observed from the innermost
$\sim1^{\circ}-2^{\circ}$ requires one or more additional recent outbursts
and/or a contribution from a centrally concentrated population of unresolved
millisecond pulsars. In order to produce a spectrum that is compatible with the
measured excess (whose shape is approximately uniform over the region of the
excess), the electrons from the older outburst must be injected with
significantly greater average energy than those injected more recently,
enabling their spectra to be similar after $\sim10^6$ years of energy losses.

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The categories of this paper are: bayes-an
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
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The categories of this paper are: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: dg-ga