Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: GRB 030226 in a Density-Jump Medium   We present an explanation for the unusual temporal feature of the GRB 030226
afterglow. The R-band afterglow of this burst faded as ~ t^{-1.2} in ~ 0.2 days
after the burst, rebrightened during the period of ~ 0.2 - 0.5 days, and then
declined with ~ t^{-2.0}. To fit such a light curve, we consider an
ultrarelativistic jetted blast wave expanding in a density-jump medium. The
interaction of the blast wave with a large density jump produces relativistic
reverse and forward shocks. In this model, the observed rebrightening is due to
emissions from these newly forming shocks, and the late-time afterglow is
caused by sideways expansion of the jet. Our fitting implies that the
progenitor star of GRB 030226 could have produced a stellar wind with a large
density jump prior to the GRB onset.

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The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: supr-con
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The categories of this paper are: econ
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The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
16
The categories of this paper are: stat
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The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph