Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The rich cluster of galaxies ABCG 85. III. Analyzing the ABCG 85/87/89
  complex   We present a combined X-ray and optical analysis of the ABCG 85/87/89 complex
of clusters of galaxies, based on the ROSAT PSPC image, optical photometric
catalogues (Slezak et al. 1998), and an optical redshift catalogue (Durret et
al. 1998). From this combined data set, we find striking alignments at all
scales at PA$\simeq$160\deg. At small scales, the cD galaxy in ABCG 85 and the
brightest galaxies in the cluster are aligned along this PA. At a larger scale,
X-ray emission defines a comparable PA south-southeast of ABCG 85 towards ABCG
87, with a patchy X-ray structure very different from the regular shape of the
optical galaxy distribution in ABCG 87. The galaxy velocities in the ABCG 87
region show the existence of subgroups, which all have an X-ray counterpart,
and seem to be falling onto ABCG 85 along a filament almost perpendicular to
the plane of the sky. To the west of ABCG 85, ABCG 89 appears as a significant
galaxy density enhancement, but is barely detected at X-ray wavelengths. The
galaxy velocities reveal that in fact this is not a cluster but two groups with
very different velocities superimposed along the line of sight. These two
groups appear to be located in intersecting sheets on opposite sides of a large
bubble. These data and their interpretation reinforce the cosmological scenario
in which matter, including galaxies, groups and gas, falls onto the cluster
along a filament.

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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex