Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Extreme X-ray Iron Lines in Active Galactic Nuclei   We analyze X-ray spectra of heavily obscured (N_H > 10^{24} cm^{-2}) active
galaxies obtained with Chandra, concentrating on the iron K alpha fluorescence
line. We measure very large equivalent widths in most cases, up to 5 keV in the
most extreme example. The geometry of an obscuring torus of material near the
active galactic nucleus (AGN) determines the Fe emission, which we model as a
function of torus opening angle, viewing angle, and optical depth. The
starburst/AGN composite galaxies in this sample require small opening angles.
Starburst/AGN composite galaxies in general therefore present few direct lines
of sight to their central engines. These composite galaxies are common, and
their large covering fractions and heavy obscuration effectively hide their
intrinsically bright X-ray continua. While few distant obscured AGNs have been
identified, we propose to exploit their signature large Fe K alpha equivalent
widths to find more examples in X-ray surveys.

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The categories of this paper are: hep-ph
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The categories of this paper are: stat
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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: quant-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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The categories of this paper are: econ
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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: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-ex