Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A variable Quasi-Periodic Ocillation in M82 X-1. Timing and spectral
  analysis of XMM-Newton and RossiXTE observations   We report results from a spectral and timing analysis of M82 X-1, one of the
brightest known ultraluminous X-ray sources. Data from a new 105 ks {\it
XMM-Newton} observation of M82 X-1, performed in April 2004, and of archival
{\it RossiXTE} observations are presented. A very soft thermal component is
present in the {\it XMM} spectrum. Although it is not possible to rule out a
residual contamination from the host galaxy, modelling it with a standard
accretion disk would imply a black hole mass of $\approx 10^3 M_{\odot}$. An
emission line was also detected at an energy typical for fluorescent Fe
emission. The power density spectrum of the {\it XMM} observation shows a
variable QPO at frequency of 113 mHz with properties similar to that discovered
by Strohmayer & Mushotzky (2003). The QPO was also found in 7 archival {\it
RXTE} observations, that include those analyzed by Strohmayer & Mushotzky
(2003) and Fiorito & Titarchuk (2004). A comparison of the properties of this
QPO with those of the various types of QPOs observed in Galactic black hole
candidates strongly suggests an association with the type-C, low frequency
QPOs. Scaling the frequency inversely to the black hole mass, the observed QPO
frequency range (from 50 to 166 mHz) would yield a black hole mass anywhere in
the interval few tens to 1000 $M_\odot$.

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The categories of this paper are: ao-sci
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The categories of this paper are: math
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The categories of this paper are: nucl-ex
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-lat
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The categories of this paper are: quant-ph
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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: nlin
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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: physics
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The categories of this paper are: cs
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The categories of this paper are: eess