Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Bright Optical flash and Afterglow from the Gamma-Ray Burst GRB
  130427A   The optical light that is generated simultaneously with the x-rays and
gamma-rays during a gamma-ray burst (GRB) provides clues about the nature of
the explosions that occur as massive stars collapse to form black holes. We
report on the bright optical flash and fading afterglow from the powerful burst
GRB 130427A and present a comparison with the properties of the gamma-ray
emission that show correlation of the optical and >100 MeV photon flux light
curves during the first 7,000 seconds. We attribute this correlation to
co-generation in an external shock. The simultaneous, multi-color, optical
observations are best explained at early times by reverse shock emission
generated in the relativistic burst ejecta as it collides with surrounding
material and at late times by a forward shock traversing the circumburst
environment. The link between optical afterglow and >100 MeV emission suggests
that nearby early peaked afterglows will be the best candidates for studying
GRB emission at GeV/TeV energies.

16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
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The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org