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Astron. Astrophys. 364, 349-368 (2000)

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8. Conclusions

In this paper, we present measurements of the angular correlation function for a sample of [FORMULA] galaxies to [FORMULA], and [FORMULA] observed with the CFHT UH8K mosaic CCD camera over a contiguous area of [FORMULA]. The main conclusions are the following:

  • The amplitude of the angular correlation function of the complete sample decreases monotonically through the entire range of magnitude intervals.

  • The flattening in the decrease of the amplitude, observed by Postman et al., is marginally confirmed by our analysis.

  • The best model to fit the evolution of the amplitude of our sample is the combination of the CFRS luminosity function with mild luminosity evolution of late-type galaxies and no evolution of early-type galaxies, a [FORMULA] flat universe, a clustering evolution with [FORMULA], and a comoving correlation length of [FORMULA] Mpc at [FORMULA]. This in agreement with the local measurements of [FORMULA] with the clustering evolution predicted by CDM hierarchical clustering models.

  • Red-selected galaxies show higher amplitudes of correlation than blue selected galaxies.

The deep multi-band photometric surveys which are in preparation should determine whether these observational results on the evolution of clustering are due to an inadequate definition of the luminosity functions of the different types of galaxies or whether the actual clustering differences reflect different formation histories of disk-dominated vs bulge-dominated galaxies. Ideally, one would like to measure the spatial two-point correlation function for each galaxy type, and for different redshift intervals. The luminosity functions and their evolution with redshift must be measured accordingly in order to closely model the observed redshift distribution of the sources. Application of photometric redshift techniques (Arnouts, 2000 priv. comm.) to the deep extension of the EIS survey (da Costa & Renzini, 1999) (http://www.eso.org/science/eis ) should provide new constraints on these functions. Another deep survey which will also allow to address these issues is the LZT survey (Hickson et al., 1998), which will provide accurate redshifts to [FORMULA] and reliable spectral types for [FORMULA] galaxies to [FORMULA]. This will allow a more detailed study of the evolution of [FORMULA]. Note that the measured evolution of the clustering amplitude with redshift in these surveys might also provide useful constraints on the cosmological parameters.

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© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001