Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Intensity Distribution and Luminosity Function of the Swift Gamma-Ray
  Bursts   Using the sample of long Gamma-ray bursts (GRBs) detected by Swift-BAT before
June 2007, we measure the cumulative distribution of the peak photon fluxes
(log N - log P) of the Swift bursts. Compared with the BATSE sample, we find
that the two distributions are consistent after correcting the band pass
difference, suggesting that the two instruments are sampling the same
population of bursts. We also compare the log N - log P distributions for
sub-samples of the Swift bursts, and find evidence for a deficit (99.75%
confident) of dark bursts without optical counterparts at high peak flux
levels, suggesting different redshift or Gamma-ray luminosity distributions for
these bursts. The consistency between the log N - log P distributions for the
optically detected bursts with and without redshift measurements indicates that
the current sample of the Swift bursts with redshift measurements, although
selected heterogeneously, represents a fair sample of the non-dark bursts. We
calculate the luminosity functions of this sample in two redshift bins (z<1 and
z>1), and find a broken power-law is needed to fit the low redshift bin, where
dN/dL \propto L^{-1.27\pm0.06} for high luminosities (L_{peak} > 5e48 erg/s)
and dN/dL \propto L^{-2.3\pm0.3} at for low luminosities, confirming the
results of several studies for a population of low luminosity GRBs.

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The categories of this paper are: mtrl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-th