Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modelling the $\gamma$-ray variability of 3C 273   We investigate MeV-GeV $\gamma$-ray outbursts in 3C 273 in the frame of a
time-dependent one-zone synchrotron self-Compton (SSC) model. In this model,
electrons are accelerated to extra-relativistic energy through the stochastic
particle acceleration and evolve with the time, nonthermal photons are produced
by both synchrotron and inverse Compton scattering of synchrotron photons.
Moreover, nonthermal photons during a quiescent are produced by the
relativistic electrons in the steady state and those during a outburst are
produced by the electrons whose injection rate is changed at some time
interval. We apply the model to two exceptionally luminous $\gamma$-ray
outbursts observed by the Fermi-LAT from 3C 273 in September, 2009 and obtain
the multi-wavelength spectra during the quiescent and during the outburst
states, respectively. Our results show that the time-dependent properties of
outbursts can be reproduced by adopting the appropriate injection rate function
of the electron population.

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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: physics
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: acc-phys
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The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: cs
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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: atom-ph
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The categories of this paper are: cmp-lg