Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Eridanus - A Supergroup in the Local Universe?   We examine a possible supergroup in the direction of the Eridanus
constellation using 6dF Galaxy Survey second data release (6dFGS DR2) positions
and velocities together with 2MASS and HyperLEDA photometry. We perform a
friends-of-friends analysis to determine which galaxies are associated with
each substructure before examining the properties of the constituent galaxies.
The structure is made up of three individual groups that are likely to merge to
form a cluster of mass 7x10^13 Msolar. We conclude that this structure is a
supergroup. We also examine the colours, morphologies and luminosities of the
galaxies in the region with respect to their local projected surface density.
We find that the colours of the galaxies redden with increasing density, the
median luminosities are brighter with increasing environmental density and the
morphologies of the galaxies show a strong morphology-density relation. The
colours and luminosities of the galaxies in the supergroup are already similar
to those of galaxies in clusters, however the supergroup contains more
late-type galaxies, consistent with its lower projected surface density. Due to
the velocity dispersion of the groups in the supergroup, which are lower than
those of clusters, we conclude that the properties of the constituent galaxies
are likely to be a result of merging or strangulation processes in groups
outlying this structure.

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The categories of this paper are: hep-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-fin
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
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The categories of this paper are: eess
29
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: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: physics
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The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int