Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: GRB 081029: A Gamma-Ray Burst with a Multi-Component Afterglow   We present an analysis of the unusual optical light curve of the gamma-ray
burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine
X-ray and optical observations from the Swift X-Ray Telescope and the Swift
UltraViolet/Optical Telescope with ground-based optical and infrared data
obtained using the REM, ROTSE, and CTIO 1.3-m telescopes to construct a
detailed data set extending from 86 s to approximately 100,000 s after the BAT
trigger. Our data cover a wide energy range, from 10 keV to 0.77 eV (1.24 to
16,000 Angstrom). The X-ray afterglow shows a shallow initial decay followed by
a rapid decay starting at about 18,000 s. The optical and infrared afterglow,
however, shows an uncharacteristic rise at about 3000 s that does not
correspond to any feature in the X-ray light curve. Our data are not consistent
with synchrotron radiation from a jet interacting with an external medium, a
two-component jet, or continuous energy injection from the central engine. We
find that the optical light curves can be broadly explained by a collision
between two ejecta shells within a two-component jet. A growing number of
gamma-ray burst afterglows are consistent with complex jets, which suggests
that some (or all) gamma-ray burst jets are complex and will require detailed
modelling to fully understand them.

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The categories of this paper are: plasm-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: gr-qc
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The categories of this paper are: math
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ph
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The categories of this paper are: cs
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th