Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray Spectra from MHD Simulations of Accreting Black Holes   We present the results of a new global radiation transport code coupled to a
general relativistic magneto-hydrodynamic simulation of an accreting,
non-rotating black hole. For the first time, we are able to explain from first
principles in a self-consistent way all the components seen in the X-ray
spectra of stellar-mass black holes, including a thermal peak and all the
features associated with strong hard X-ray emission: a power-law extending to
high energies, a Compton reflection hump, and a broad iron line. Varying only
the mass accretion rate, we are able to reproduce a wide range of X-ray states
seen in most galactic black hole sources. The temperature in the corona is T_e
~ 10 keV in a boundary layer near the disk and rises smoothly to T_e >~ 100 keV
in low-density regions far above the disk. Even as the disk's reflection edge
varies from the horizon out to ~ 6M as the accretion rate decreases, we find
that the shape of the Fe K\alpha line is remarkably constant. This is because
photons emitted from the plunging region are strongly beamed into the horizon
and never reach the observer. We have also carried out a basic timing analysis
of the spectra and find that the fractional variability increases with photon
energy and viewer inclination angle, consistent with the coronal hot spot model
for X-ray fluctuations.

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The categories of this paper are: solv-int
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The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
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The categories of this paper are: q-bio
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The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
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The categories of this paper are: chao-dyn
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The categories of this paper are: cond-mat
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: cs
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The categories of this paper are: alg-geom