Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comparing Correlation Lengths of Red and Blue Galaxies: A New Standard
  Length for Testing Cosmic Isotropy   I introduce a simple empirical measure of average galaxy cluster sizes based
on a comparison of the correlation lengths of red galaxies with blue that can
provide a more accurate and bias-free measure of the average size and number
density of galaxy clusters. Using 269,000 galaxies from the SDSS DR6 survey, I
show that this 3D correlation length, averaged over many clusters, remains very
nearly constant at L0= 4.797 +/- 0.024 Mpc/h from small redshifts out to
redshifts of 0.5. This serves as a new measure of cosmic length scales and
provides a means of testing the standard cosmological model that is almost free
of selection biases. The unprecedented accuracy of the technique allows the
possibility of sensitive searches for large-scale inhomogeneities. Applying the
same technique to the Millennium Simulation galaxies I find very good agreement
between it and the SDSS galaxies.

31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
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The categories of this paper are: adap-org