Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the variability of the iron line in Mrk 841   Petrucci et al. (2002; hereafter P02) have reported extraordinary behaviour
of the iron K alpha line in the type 1 AGN Mrk 841. At the XMM-Newton/EPIC
resolution, a narrow line was observed in a short observation, which then
apparently disappeared around 0.5 days later when another observation was
performed. The limits are such that the line cannot both be narrow, and
variable at this level, as the light-travel time places the material at a
radius where broadening by the black hole's gravitational field is inevitable.
Adding an additional observation taken before the P02 data, we present a
different interpretation of the apparent variability. The data support the
hypothesis that the line in fact varies in width, not only in flux. Rather than
showing no line, and despite the strong Compton reflection component, the final
observation exhibits broad emission at ~ 6.2-6.4 keV, with a width of ~0.8 keV,
typical of a relativistic accretion disc. We suggest that the apparently narrow
line in the early observations arises from local illumination by a flare
inducing an hotspot in the inner disc, which then becomes progressively
broadened as the disc rotates.

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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: hep-ex
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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: cs
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The categories of this paper are: physics
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-th
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-th
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The categories of this paper are: bayes-an
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The categories of this paper are: math