Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anatomy of a Merger: A Numerical Model of A754   A754 is a well-observed cluster of galaxies which exhibits a variety of
morphological peculiarities. These include a bar of X-ray emission that is
offset significantly from the galaxy distribution, an elongated X-ray surface
brightness distribution extending between two distinct peaks in the galaxy
distribution, and an extremely non-isothermal and asymmetric intracluster
medium (ICM) temperature morphology. Using these observational constraints, we
present a numerical Hydro/N-body model of A754 in which two clusters (2.5:1
mass ratio) have merged nearly in the plane of the sky less than 0.5 Gyrs ago
with an impact parameter of ~120 kpc, and an impact velocity of ~2500 km/s
(roughly the escape velocity of the primary cluster). Our models allow us to
identify the origin of A754's peculiar X-ray and temperature morphologies, the
underlying hydrodynamical processes that shape them, and their future
evolution. We make detailed predictions for future high resolution X-ray
spectroscopic observations (e.g. ASTRO-E). We discuss general properties of our
models which will be characteristic of off-axis mergers. In particular, we find
significant non-thermal pressure support within the central region which could
bias cluster mass estimates. We find significant angular momentum imparted on
the gas distribution in the cluster. We find that mixing of the subcluster gas
components is an inefficient process, particularly at large radii. Finally, we
find that subsequent dark matter core passages result in an extended relaxation
timescale.

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The categories of this paper are: math-ph
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The categories of this paper are: q-fin
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The categories of this paper are: alg-geom
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The categories of this paper are: math
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: solv-int
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The categories of this paper are: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
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The categories of this paper are: hep-ph