Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Precise Measurement of the Spin Parameter of the Stellar-Mass Black Hole
  M33 X-7   In prior work, {\it Chandra} and Gemini-North observations of the eclipsing
X-ray binary M33 X-7 have yielded measurements of the mass of its black hole
primary and the system's orbital inclination angle of unprecedented accuracy.
Likewise, the distance to the binary is known to a few percent. In an analysis
based on these precise results, fifteen {\it Chandra} and {\it XMM-Newton}
X-ray spectra, and our fully relativistic accretion disk model, we find that
the dimensionless spin parameter of the black hole primary is $a_* = 0.77 \pm
0.05$. The quoted 1-$\sigma$ error includes all sources of observational
uncertainty. Four {\it Chandra} spectra of the highest quality, which were
obtained over a span of several years, all lead to the same estimate of spin to
within statistical errors (2%), and this estimate is confirmed by 11 spectra of
lower quality. There are two remaining uncertainties: (1) the validity of the
relativistic model used to analyze the observations, which is being addressed
in ongoing theoretical work; and (2) our assumption that the black hole spin is
approximately aligned with the angular momentum vector of the binary, which can
be addressed by a future X-ray polarimetry mission.

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The categories of this paper are: hep-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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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: q-bio
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The categories of this paper are: funct-an
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
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The categories of this paper are: patt-sol
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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: cond-mat
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The categories of this paper are: physics