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The ESO Slice Project (ESP) galaxy redshift survey *
VII. The redshift and real-space correlation functions
L. Guzzo 1,
J.G. Bartlett 2,
A. Cappi 3,
S. Maurogordato 4,
E. Zucca 3,5,
G. Zamorani 3,5,
C. Balkowski 6,
A. Blanchard 2,
V. Cayatte 6,
G. Chincarini 1,7,
C.A. Collins 8,
D. Maccagni 9,
H. MacGillivray 10,
R. Merighi 3,
M. Mignoli 3,
D. Proust 6,
M. Ramella 11,
R. Scaramella 12,
G.M. Stirpe 3 and
G. Vettolani 5
Received 12 January 1999 / Accepted 3 December 1999
We present analyses of the two-point correlation properties of the ESO Slice Project (ESP) galaxy redshift survey, both in redshift and real space. From the redshift-space correlation function we are able to trace positive clustering out to separations as large as , after which smoothly breaks down, crossing the zero value between 60 and . This is best seen from the whole magnitude-limited redshift catalogue, using the minimum-variance weighting estimator. is reasonably well described by a shallow power law with between 3 and , while on smaller scales () it has a shallower slope (). This flattening is shown to be mostly due to the redshift-space damping produced by virialized structures, and is less evident when volume-limited samples of the survey are analysed.
We examine the full effect of redshift-space distortions by computing the two-dimensional correlation function , from which we project out the real-space below . This function is well described by a power-law model , with Mpc and for the whole magnitude-limited catalogue.
Comparison to other redshift surveys shows a consistent picture in which galaxy clustering remains positive out to separations of or larger, in substantial agreement with the results obtained from angular surveys like the APM and EDSGC. Also the shape of the two-point correlation function is remarkably unanimous among these data sets, in all cases requiring more power on scales larger than (a `shoulder'), with respect to a simple extrapolation of the canonical =.
The analysis of for volume-limited subsamples with different luminosity shows evidence of luminosity segregation only for the most luminous sample with . For these galaxies, the amplitude of clustering is on all scales about a factor of 2 above that of all other subsamples containing less luminous galaxies. When redshift-space distortions are removed through projection of , however, a weak dependence on luminosity is seen at small separations also at fainter magnitudes, resulting in a growth of from to , when the limiting absolute magnitude of the sample changes from to . This effect is masked in redshift space, as the mean pairwise velocity dispersion experiences a parallel increase, basically erasing the effect of the clustering growth on .
Key words: cosmology: observations cosmology: large-scale structure of Universe
Send offprint requests to: L. Guzzo (email@example.com)
Online publication: March 17, 2000