Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Akn 564: an unusual component in the X-ray spectra of NLSy1 galaxies   We present an ASCA observation of the NLSy1 Ark 564. The X-ray light curve
shows rapid variability, but no evidence for energy-dependence to these
variations, within the 0.6 -- 10 keV bandpass. A strong (EW ~ 70 eV) spectral
feature is observed close to 1 keV. A similar feature has been observed in TON
S180 (another NLSy1) but has not been observed in broad-line Seyfert galaxies.
The feature energy suggests a large contribution from Fe L-shell lines but its
intensity is difficult to explain in terms of emission and/or absorption from
photoionized gas. Models based on gas in thermal equilibrium with kT ~1 keV
provide an alternative parameterization of the soft spectrum. The latter may be
interpreted as the hot intercloud medium, undergoing rapid cooling and
producing strong Fe L-shell recombination lines. In all cases the physical
conditions are rather different from those observed in broad-line Seyferts. The
hard X-ray spectrum shows a broad and asymmetric Fe Kalpha line of large
equivalent width (~550 eV) which can be explained by a neutral disk viewed at ~
60 degrees to the line-of-sight, contrary to the hypothesis that NLSy1s are
viewed pole-on. The large EW of this line, the strong 1 keV emission and the
strong optical Fe emission lines all suggest an extreme Fe abundance in this
and perhaps other NLSy1s.

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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: gr-qc
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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: dg-ga
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The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
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The categories of this paper are: cs
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The categories of this paper are: eess