Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The puzzling dynamical status of the core of the globular cluster NGC
  6752   We have used high resolution WFPC2-HST and ground based Wide Field images to
determine the center of gravity and construct an extended radial density and
brightness profile of the cluster NGC 6752 including, for the first time,
detailed star counts in the very inner region. The barycenter of the 9
innermost X-ray sources detected by Chandra is located only 1.9" off the new
center of gravity. Both the density and the brightness profile of the central
region are best fitted by a double King model, suggesting that NGC 6752 is
experiencing a post-core collapse "bounce". Taking advantage from our new
optical data, we discuss the puzzling nature of the accelerations displayed by
the innermost millisecond pulsars detected in this cluster. We discuss two
possible origins to the accelerations: 1) the overall cluster gravitational
potential which would require a central projected mass to light ratio of order
6-7 and the existence of a few thousand solar masses of low-luminosity matter
within the inner 0.08 pc of NGC6752; 2) the existence of a local perturber(s)
of the pulsar dynamics, such as a recently proposed binary black hole of
intermediate (100-$200 Msun) mass.

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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
2
The categories of this paper are: math
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The categories of this paper are: econ
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int