We have carried out an investigation of clustering evolution of field galaxies between a redshift of z~1 and the present epoch. The current analysis relies on a sample of ~14,000 galaxies from the COMBO-17 survey. The redshift distribution extends to z~1. The amplitude of the three-dimensional correlation function can be estimated by means of the projected correlation function w(r_p). The validity of the deprojection was tested on the Las Campanas Redshift Survey (LCRS, see Shectman et al. 1996). The LCRS sample, which consists mainly of intrinsically bright galaxies, is also used as local measurement.

Since it is well known that bright galaxies are stronger clustered than the faint ones which dominate the COMBO-17 sample at redshifts z~0.3, we calculated the correlation function for a subsample bright galaxies (M_B<-18), to facilitate a direct comparison with the LCRS. Extreme starbursts are exluded, since their redshift errors are too large to obtain reliable estimates of the clustering strength.

In a flat cosmology with non-zero cosmological constant for bright galaxies the clustering growth is proportional to (1+z)^-2. However, the measured clustering evolution clearly also depends on Hubble type. At higher redshifts early type galaxies are much stronger clustered, and the structure grows much slower. At redshifts z>0.2, early type galaxies are highly biased tracers of the underlying dark matter density distribution. At the present epoch the relative bias has decreased, the amplitudes of bright and early type galaxies converge to the same value at z=0.

Contact person: Stefanie Phleps, MPIA

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