Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chandra X-ray Analysis of Galaxy Cluster A168   We present Chandra X-ray observations of galaxy cluster A168 (z=0.045). Two
X-ray peaks with a projected distance of 676 kpc are found to be located close
to two dominant galaxies, respectively. Both peaks are significantly offset
from the peak of the number density distribution of galaxies. This suggests
that A168 consists of two subclusters, a northern subcluster (A168N) and a
southern subcluster (A168S). Further X-ray imaging analysis reveals that (1)
the X-ray isophotes surrounding the two X-ray peaks are heavily distorted, (2)
an elongated and ontinuous filament connects the two X-ray peaks. These suggest
that strong interactions have occurred between the two subclusters. Spectral
analysis shows that A168 has a mean temperature of 2.53 +/- 0.09 keV and a mean
metallicity of 0.31 +/- 0.04 Z_{solar}. The metallicity is roughly a constant
across the cluster but the temperature shows some systematic variations. Most
X-ray, optical and radio properties of A168 are consistent with it being an
off-axis merger several Gyrs after a core passage, although detailed numerical
simulations are required to see whether the observed properties, in particular
the significant offset between the optical and X-ray centers, can be reproduced
in such a scenario.

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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: atom-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: physics
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The categories of this paper are: econ
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The categories of this paper are: patt-sol
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The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc