Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gamma Ray Bursts Are Observed Off-Axis   We use the ScaleFit package to perform Markov chain Monte Carlo light curve
fitting on a large sample of Swift-XRT gamma-ray burst afterglows. The ScaleFit
model uses scaling relations in the hydrodynamic and radiation equations to
compute synthetic light curves directly from a set of high resolution
two-dimensional relativistic blast wave simulations. The data sample consists
of all Swift-XRT afterglows from 2005 to 2012 with sufficient coverage and a
known redshift, 188 bursts in total. We find the jet half opening angle varies
widely but is commonly less than 0.1 radians. The distribution of the electron
spectral index is also broad, with a median at 2.23. This approach allows, for
the first time, for the off-axis observer angle to be inferred directly from
the light curve. We find the observer angle to have a median value of 0.57 of
the jet opening angle over our sample, which has profound consequences for the
predicted rate of observed jet breaks and effects the beaming corrected total
energies of gamma-ray bursts.

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The categories of this paper are: math-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: supr-con
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The categories of this paper are: hep-th
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: cs