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Astron. Astrophys. 355, 1-16 (2000)

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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

1 Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate (LC), Italy
2 Observatoire Astronomique, Université Louis Pasteur, 11 rue de l'Université, 67000 Strasbourg, France unité associée au CNRS - UMR7550
3 Osservatorio Astronomico di Bologna, via Zamboni 33, 40126 Bologna, Italy
4 CERGA, Observatoire de la Côte d'Azur, 06304 Nice Cedex 4, France
5 Istituto di Radioastronomia del CNR, via Gobetti 101, 40129 Bologna, Italy
6 Observatoire de Paris, DAEC, 5 Pl. J.Janssen, 92195 Meudon, France
7 Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano, Italy
8 School of Engineering, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK
9 Istituto di Fisica Cosmica e Tecnologie Relative, via Bassini 15, 20133 Milano, Italy
10 Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
11 Osservatorio Astronomico di Trieste, via Tiepolo 11, 34131 Trieste, Italy
12 Osservatorio Astronomico di Roma, via Osservatorio 2, 00040 Monteporzio Catone (RM), Italy

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 [FORMULA] we are able to trace positive clustering out to separations as large as [FORMULA], after which [FORMULA] smoothly breaks down, crossing the zero value between 60 and [FORMULA]. This is best seen from the whole magnitude-limited redshift catalogue, using the [FORMULA] minimum-variance weighting estimator. [FORMULA] is reasonably well described by a shallow power law with [FORMULA] between 3 and [FORMULA], while on smaller scales ([FORMULA]) it has a shallower slope ([FORMULA]). 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 [FORMULA] , from which we project out the real-space [FORMULA] below [FORMULA]. This function is well described by a power-law model [FORMULA], with [FORMULA] Mpc and [FORMULA] 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 [FORMULA] 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 [FORMULA] (a `shoulder'), with respect to a simple extrapolation of the canonical [FORMULA] =[FORMULA].

The analysis of [FORMULA] for volume-limited subsamples with different luminosity shows evidence of luminosity segregation only for the most luminous sample with [FORMULA]. For these galaxies, the amplitude of clustering is on all scales [FORMULA] about a factor of 2 above that of all other subsamples containing less luminous galaxies. When redshift-space distortions are removed through projection of [FORMULA] , however, a weak dependence on luminosity is seen at small separations also at fainter magnitudes, resulting in a growth of [FORMULA] from [FORMULA] to [FORMULA], when the limiting absolute magnitude of the sample changes from [FORMULA] to [FORMULA]. 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 [FORMULA] .

Key words: cosmology: observations – cosmology: large-scale structure of Universe

* Based on observations collected at the European Southern Observatory, La Silla, Chile.

Send offprint requests to: L. Guzzo (guzzo@merate.mi.astro.it)

© European Southern Observatory (ESO) 2000

Online publication: March 17, 2000