Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: GRB 090902B: afterglow observations and implications   The optical-infrared afterglow of the LAT-detected long duration burst, GRB
090902B, has been observed by several instruments. The earliest detection by
ROTSE-IIIa occurred 80 minutes after detection by the GBM instrument onboard
the Fermi Gamma-Ray Space Telescope, revealing a bright afterglow and a decay
slope suggestive of a reverse shock origin. Subsequent optical-IR observations
followed the light curve for 6.5 days. The temporal and spectral behavior at
optical-infrared frequencies is consistent with synchrotron fireball model
predictions; the cooling break lies between optical and XRT frequencies ~ 1.9
days after the burst. The inferred electron energy index is $p = 1.8 \pm 0.2$,
which would however imply an X-ray decay slope flatter than observed. The XRT
and LAT data have similar spectral indices and the observed steeper value of
the LAT temporal index is marginally consistent with the predicted temporal
decay in the radiative regime of the forward shock model. Absence of a jet
break during the first 6 days implies a collimation-corrected $\gamma$-ray
energy $E_{\gamma} > 2.2\times10^{52}\rm$ ergs, one of the highest ever seen in
a long-duration GRBs. More events combining GeV photon emission with
multi-wavelength observations will be required to constrain the nature of the
central engine powering these energetic explosions and to explore the
correlations between energetic quanta and afterglow emission.

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The categories of this paper are: math-ph
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The categories of this paper are: q-alg
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The categories of this paper are: q-bio
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The categories of this paper are: hep-ex
3
The categories of this paper are: physics
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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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: hep-lat
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The categories of this paper are: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th