Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: GRB Theory in the Fermi Era   Before the launch of the Fermi Gamma-ray Space Telescope there were only a
handful of gamma-ray bursts (GRBs) detected at high energies (above 100 MeV),
while several different suggestions have been made for possible high-energy
emission sites and mechanisms. Here I briefly review some of the theoretical
expectations for high-energy emission from GRBs, outline some of the hopes for
improving our understanding of GRB physics through Fermi observations of the
prompt GRB emission or the early afterglow (first few hours after the GRB), and
summarize what we have learned so far from the existing Fermi GRB observations
(over its first half-year of operation). Highlights include the first detection
of > GeV emission from a short GRB, as well as detailed temporal and spectral
information for the first GRB with > GeV emission and a measured redshift, that
has the highest measured apparent (isotropic equivalent) radiated energy output
(for any GRB), the largest lower limit on the bulk Lorentz factor of the
emitting region, and constrains possible Lorentz invariance violation by
placing a robust lower limit on the quantum gravity mass.

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The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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The categories of this paper are: cond-mat