Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Milliarcsecond-Scale Structure in the Gamma-Ray Loud Quasar PKS 1622-297   We have made a high-resolution VLBI observation of the gamma-ray loud quasar
PKS 1622-297 with the HALCA spacecraft and ground radio telescopes at 5 GHz in
1998 February, almost three years after the source exhibited a spectacular GeV
gamma-ray flare. The source shows an elongated structure toward the west on the
parsec scale. The visibility data are well modeled by three distinct
components; a bright core and two weaker jet components. Comparison with
previous observations confirms that the jet components have an apparent
superluminal motion up to 12.1 h^{-1}c, with the inner jet components having
lower superluminal speeds. We apply the inverse Compton catastrophe model and
derive a Doppler factor, \delta, of 2.45, which is somewhat lower than that of
other gamma-ray loud active galactic nuclei (AGNs), suggesting the source was
in a more quiescent phase at the epoch of our observation. As an alternative
probe of the sub-parsec scale structure, we also present the results from
multi-epoch ATCA total flux monitoring, which indicate the presence of
persistent intraday variability consistent with refractive interstellar
scintillation. We examine the gamma-ray emission mechanism in the light of
these observations.

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The categories of this paper are: supr-con
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The categories of this paper are: eess
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The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: math
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: physics
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The categories of this paper are: econ
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg