Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The outer halo globular cluster system of M31 - II. Kinematics   We present a detailed kinematic analysis of the outer halo globular cluster
(GC) system of M31. Our basis for this is a set of new spectroscopic
observations for 78 clusters lying at projected distances between Rproj ~20-140
kpc from the M31 centre. These are largely drawn from the recent PAndAS
globular cluster catalogue; 63 of our targets have no previous velocity data.
Via a Bayesian maximum likelihood analysis we find that GCs with Rproj > 30 kpc
exhibit coherent rotation around the minor optical axis of M31, in the same
direction as more centrally- located GCs, but with a smaller amplitude of
86+/-17 km s-1. There is also evidence that the velocity dispersion of the
outer halo GC system decreases as a function of projected distance from the M31
centre, and that this relation can be well described by a power law of index ~
-0.5. The velocity dispersion profile of the outer halo GCs is quite similar to
that of the halo stars, at least out to the radius up to which there is
available information on the stellar kinematics. We detect and discuss various
velocity correlations amongst subgroups of GCs that lie on stellar debris
streams in the M31 halo. Many of these subgroups are dynamically cold,
exhibiting internal velocity dispersions consistent with zero. Simple Monte
Carlo experiments imply that such configurations are unlikely to form by
chance, adding weight to the notion that a significant fraction of the outer
halo GCs in M31 have been accreted alongside their parent dwarf galaxies. We
also estimate the M31 mass within 200 kpc via the Tracer Mass Estimator,
finding (1.2 - 1.6) +/- 0.2 10^{12}M_sun. This quantity is subject to
additional systematic effects due to various limitations of the data, and
assumptions built in into the TME. Finally, we discuss our results in the
context of formation scenarios for the M31 halo.

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The categories of this paper are: gr-qc
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The categories of this paper are: q-bio
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-th
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: adap-org
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The categories of this paper are: physics
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The categories of this paper are: q-alg
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The categories of this paper are: acc-phys