Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The ROSAT BRIGHT survey: I. Identification of an AGN sample with hard
  ROSAT X-ray spectra   The ROSAT Bright Survey (RBS) aims to completely optically identify the more
than 2000 brightest sources detected in the ROSAT all-sky survey at galactic
latitudes |b| > 30 degr (excluding LMC, SMC, Virgo cluster). This paper
presents a subsample of 66 bright point-like ROSAT survey sources with almost
hard PSPC spectra, the hardness ratio HR1 is > 0.5 for most of the sources. The
subsample could be nearly completely identified by low-resolution optical
spectroscopy with the following breakdown into object classes: 31 Seyfert
galaxies, 22 BL Lac candidates, 5 clusters of galaxies 1 cataclysmic variable,
and 5 bright stars. Only one object remained unidentified and one X-ray source
was a spurious detect ion. The redshift distribution peaks around 0.06 for the
Seyferts and around 0.13 for the BL Lac candidates. Observations with medium
spectral resolution were obtained for most of the new S eyfert galaxies. A
large fraction (20 objects) are type 1 Seyfert galaxies, the other fraction
includes Seyfert galaxies of type 1.5 - 1.8 (5 objects), two LINERs, and 4
possible narrow-line Seyfert 1 galaxies (NLS1). About one third of the new
Seyfert's have nearby companion galaxies displaying either emission or
absorption lines at the same redshift. Among them are a couple of systems
showing direct morphological evidence for interaction. The large fraction of
interacting galaxies among our sample suggests a scenario where interaction is
the main trigger of AGN activity.

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The categories of this paper are: chem-ph
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The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
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The categories of this paper are: eess
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-th
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: chao-dyn