Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Homogeneity of early-type galaxies across clusters   We studied the homogeneity, across clusters, of the color of the red sequence
(the intercept of the color--magnitude relation) of 158 clusters and groups
detected in the Early Data Release of the Sloan Digital Sky Survey (EDR-SDSS)
in the redshift range 0.06<z<0.34. We found a high degree of homogeneity: the
color of the red sequence shows an intrinsic scatter of 0.02 mag across
clusters, suggesting that either galaxies on the red sequence formed a long
time ago (z>2) or else their star formation is universally delayed with
preservation of a small spread in age formation. The latter possibility is
ruled out by the mere existence of galaxies at high redshift. While the old age
of ellipticals was already been claimed for a small heterogeneous collection of
clusters, most of which are rich ones, we found that it holds for ten to one
hundred large sample, representative of all clusters and groups detected on the
EDR-SDSS. Hence we suggest the possible universality of the color of the
galaxies on the red sequence. The observed red sequence color does not depend
on cluster/group richness at a level of 0.02 mag, while a ~0.23 mag effect is
expected according to the hierarchical prediction. Therefore, the stellar
population of red sequence galaxies is similar in clusters and groups, in spite
of different halo histories. Finally, since the observed rest--frame color of
the red sequence does not depend on environment and redshift, it can be used as
a distance indicator, with an error sigma_z=0.018. [Abridged]

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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: adap-org
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The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph
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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: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: eess
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The categories of this paper are: dg-ga
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The categories of this paper are: cs
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
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The categories of this paper are: stat
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The categories of this paper are: supr-con