Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Gamma-Ray Burst/Pulsar for Cosmic-Ray Positrons with a Dark
  Matter-like Spectrum   We propose that a nearby gamma-ray burst (GRB) or GRB-like (old, single and
short-lived) pulsar/supernova remnant/microquasar about 10^{5-6} years ago may
be responsible for the excesses of cosmic-ray positrons and electrons recently
observed by the PAMELA, ATIC/PPB-BETS, Fermi and HESS experiments. We can
reproduce the smooth Fermi/HESS spectra as well as the spiky ATIC/PPB-BETS
spectra. The spectra have a sharp cutoff that is similar to the dark matter
predictions, sometimes together with a line (not similar), since higher energy
cosmic-rays cool faster where the cutoff/line energy marks the source age. A
GRB-like astrophysical source is expected to have a small but finite spread in
the cutoff/line as well as anisotropy in the cosmic-ray and diffuse gamma-ray
flux, providing a method for the Fermi and future CALET experiments to
discriminate between dark matter and astrophysical origins.

28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas