Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hard X-Ray Spectra of Broad-Line Radio Galaxies from the Rossi X-Ray
  Timing Explorer   We present the results of hard-X-ray observations of four broad-line radio
galaxies (BLRGs) with the Rossi X-Ray Timing Explorer (RXTE). The original
motivation behind the observations was to search for systematic differences
between the BLRGs and their radio-quiet counterparts, the Seyfert galaxies. We
do, indeed, find that the Fe K-alpha lines and Compton "reflection" components,
which are hallmarks of the X-ray spectra of Seyferts galaxies, are weaker in
BLRGs by about a factor of 2. This observational result is in agreement with
the conclusions of other recent studies of these objects. We examine several
possible explanations for this systematic difference, including beaming of the
primary X-rays away from the accretion disk, a low iron abundance, a small
solid angle subtended by the disk to the primary X-ray source, and dilution of
the observed spectrum by beamed X-rays from the jet. We find that a small solid
angle subtended by the disk to the primary X-ray source is a viable and
appealing explanation, while all others suffer from drawbacks. We interpret
this as an indication of a difference in the inner accretion disk structure
between Seyfert galaxies and BLRGs, namely that the inner accretion disks of
BLRGs have the form of an ion-supported torus or an advection-dominated
accretion flow, which irradiates the geometrically thin outer disk.

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The categories of this paper are: dg-ga
1
The categories of this paper are: cs
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The categories of this paper are: solv-int
3
The categories of this paper are: physics
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The categories of this paper are: q-alg
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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: hep-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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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: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: alg-geom