Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Limits on an Intermediate Mass Black Hole in Omega Centauri: I.
  Hubble Space Telescope Photometry and Proper Motions   We analyze data from the Hubble Space Telescope's Advanced Camera for Surveys
of the globular cluster Omega Cen. We construct a photometric and proper-motion
catalog using the GO-9442, GO-10252, and GO-10775 data sets. The 2.5- to 4-year
baseline between observations yields a catalog of some 10^5 proper motions,
with 53,382 high-quality measurements in a central field. We determine the
cluster center to ~1-arcsecond accuracy using two different star-count methods,
and a completely independent method using 2MASS images. We also determine the
kinematical center of the proper motions, which agrees with the star-count
center to within its uncertainty. The proper-motion dispersion of the cluster
increases gradually inwards, but there is no variation in kinematics with
position within the central ~15 arcsec: there is no dispersion cusp and no
stars with unusually high velocities. We measure for the first time in any
globular cluster the variation in proper-motion dispersion with mass along the
main sequence, and find the cluster not yet to be in equipartition. Our
proper-motion results do not confirm the arguments put forward by Noyola,
Gebhardt & Bergmann to suspect an intermediate-mass black hole (IMBH) in Omega
Cen. In Paper II we present new dynamical models for the high-quality data
presented here, with the aim of putting quantitative contraints on the mass of
any possible IMBH.

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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: supr-con
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The categories of this paper are: hep-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: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: econ