Issue |
A&A
Volume 457, Number 1, October I 2006
|
|
---|---|---|
Page(s) | 145 - 155 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20053626 | |
Published online | 12 September 2006 |
Galaxy clustering from COMBO-17: the halo occupation
distribution at
= 0.6
1
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
2
Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany e-mail: sphleps@mpe.mpg.de
3
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
4
Department of Physics, University of Oxford, Denys Wilkinson Building., Keble Road, Oxford OX1 3RH, UK
Received:
14
June
2005
Accepted:
26
June
2006
We present measurements of galaxy clustering at redshift
using
galaxies with photometric redshifts
over an area of 0.78 deg2 from the COMBO-17 survey. To obtain a result
that is unaffected by redshift uncertainties, we calculate the
projected correlation function
, giving results for red sequence and blue
cloud galaxies separately. The correlation function of the red galaxies displays
clear deviations from a power law at comoving separations
around 1 to
, and similar but weaker trends are suggested
by the data for the blue galaxies. To interpret these results, we fit the correlation
functions with analytical predictions derived from a simple halo occupation model.
This combines linear clustering of the underlying mass with
a description of the number of galaxies occupying each dark-matter halo
(the halo occupation distribution).
If the occupation numbers are taken to be a simple
power law
, then
and
for red and blue galaxies respectively.
These figures are little different from the values required to fit
present-day clustering data. The power-spectrum shape is assumed
to be known in this exercise, but we allow the data to determine
the preferred value of
, the linear power-spectrum normalization.
The average normalization inferred from
red and blue galaxies at
is
at zero redshift,
consistent with independent estimates of this local value.
This agreement can be regarded as a verification of the
hierarchical growth of the halo mass function.
Key words: large-scale structure of Universe / galaxies: statistics / cosmological parameters
© ESO, 2006
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