Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discovery of gamma-ray emission from the Broad Line Radio Galaxy Pictor
  A   We report the discovery of high-energy \gamma-ray emission from the Broad
Line Radio Galaxy (BLRG) Pictor A with a significance of ~5.8\sigma (TS=33.4),
based on three years of observations with the Fermi Large Area Telescope (LAT)
detector. The three-year averaged E>0.2 GeV \gamma-ray spectrum is adequately
described by a power-law, with a photon index, \Gamma, of $2.93 \pm 0.03$ and a
resultant integrated flux of $F_{\gamma}=(5.8\pm0.7) \times 10^{-9}$ ph
cm$^{-2}$s$^{-1}$.
  A temporal investigation of the observed \gamma-ray flux, which binned the
flux into year long intervals, reveals that the flux in the third year was 50%
higher than the three-year average flux. This observation, coupled with the
fact that this source was not detected in the first two years of {Fermi-LAT
observations, suggests variability on timescales of a year or less.
  Synchrotron Self-Compton modelling of the spectral energy distribution of a
prominent hot-spot in Pictor A's western radio lobe is performed. It is found
that the models in which the \gamma-ray emission originates within the lobes,
predicts an X-ray flux larger than that observed. Given that the X-ray emission
in the radio lobe hot-spots has been resolved with the current suite of X-ray
detectors, we suggest that the \gamma-ray emission from Pictor A originates
from within its jet, which is in agreement with other \gamma-ray loud BLRGs.
This suggestion is consistent with the evidence that the \gamma-ray flux is
variable on timescales of a year or less.

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The categories of this paper are: cond-mat
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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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The categories of this paper are: cs
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The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: econ