Issue |
A&A
Volume 465, Number 1, April I 2007
|
|
---|---|---|
Page(s) | 23 - 33 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20065321 | |
Published online | 22 January 2007 |
Power law correlations in galaxy distribution and finite volume effects from the Sloan Digital Sky Survey Data Release Four
1
“Enrico Fermi Center”, via Panisperna 89 A, Compendio del Viminale, 00184 Rome, Italy e-mail: sylos@romal.infn.it
2
“Istituto dei Sistemi Complessi” CNR, via dei Taurini 19, 00185 Rome, Italy
3
Institute of Astronomy, St. Petersburg State University, Staryj Peterhoff, 198504 St. Petersburg, Russia
Received:
30
March
2006
Accepted:
18
October
2006
We discuss the estimation of galaxy correlation properties in several
volume limited samples, in different sky regions, obtained from the
Fourth Data Release of the Sloan Digital Sky Survey. The small scale
properties are characterized through the determination of the nearest
neighbor probability distribution. By using a very conservative
statistical analysis, in the range of scales [ 0.5, ~30] Mpc/h we
detect power-law correlations in the conditional density in redshift
space, with an exponent . This behavior is stable
in all the different samples we considered; thus it does not depend on
galaxy luminosity. In the range of scales [ ~30, ~100] Mpc/h
we find evidence for systematic unaveraged fluctuations and we
discuss in detail the problems induced by finite volume effects on the
determination of the conditional density. We conclude that in such a range of scales there is evidence for a smaller power-law index of
the conditional density. However we cannot distinguish between two possibilities: (i) that a crossover to homogeneity (corresponding to
in the conditional density) occurs before 100 Mpc/h; (ii) that correlations extend to scales of order 100 Mpc/h (with a smaller
exponent
). We emphasize that galaxy distributions in
these samples present large fluctuations at the largest scales probed,
corresponding to the presence of large scale structures extending up
to the boundaries of the present survey. We discuss several
differences between the behavior of the conditional density in mock
galaxy catalogs built from cosmological N-body simulations and real
data. We discuss some theoretical implications of such differences
considering also the super-homogeneous features of primordial density
fields.
Key words: cosmology: observations / large-scale structure of Universe
© ESO, 2007
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