Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fermi/LAT discovery of gamma-ray emission from a relativistic jet in the
  narrow-line Seyfert 1 quasar PMN J0948+0022   We report the discovery by the Large Area Telescope (LAT) onboard the Fermi
Gamma-ray Space Telescope of high-energy gamma-ray emission from the peculiar
quasar PMN J0948+0022 (z=0.585+/-0.001). Contrary to the expectations, the
optical spectrum of this quasar shows only narrow lines [FWHM(Hbeta) ~ 1500
km/s] and the typical characteristics of narrow-line Seyfert 1 type galaxies.
However, the strong radio emission and the flat spectrum suggest the presence
of a relativistic jet, which can now be confirmed by the detection of MeV-GeV
photons. PMN J0948+0022 is therefore the first radio-loud narrow-line Seyfert 1
quasar to be detected at gamma-rays and the third type of gamma-ray emitting
AGN, after blazars and radiogalaxies.

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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas