Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An extreme gravitationally redshifted iron line at 4.8 keV in Mrk 876   X-ray spectral lines at unforeseen energies are important because they can
shed light on the extreme physical conditions of the environment around the
supermassive black holes of active galactic nuclei (AGN). Mrk 876 displays such
a line at 4.8 keV rest-frame energy. A possible interpretation of its origin
can be found in the hotspot scenario. In this scenario the primary radiation
from a flare in the hot corona of an AGN illuminates a limited portion of the
accretion disk that emits by fluorescence. In this context the line can
represent an extreme gravitationally redshifted Fe line originating on the
accretion disk below 6 gravitational radii from a rotating supermassive black
hole. The correct estimate of the line significance requires a dedicated
approach. Based on an existing rigorous approach, we have performed extensive
Monte Carlo simulations. We determine that the line is a real feature at ~99
confidence level.

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The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: eess
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The categories of this paper are: math-ph
18
The categories of this paper are: econ
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin