Large-Scale Structure at the Turn of the Millennium

Abstract

I review the current status of studies of the large-scale structure of the Universe using redshift surveys of galaxies and clusters of galaxies. I first summarise the advances we have made in our knowledge of the cosmography of the z<0.2 Universe during the last 25 years, as well as the status of the major surveys in progress. The question of how the &#34;a priori&#34; selection of some classes of objects &#34;biases&#34; the mapping of the underlying mass density field is discussed in some detail. I then emphasise the advantages of using clusters of galaxies selected in the X-ray band as tracers of large--scale structure, summarising the most recent results of the REFLEX survey, which is under completion. The strong potential of using X-ray clusters to study the evolution of structure to large redshifts is underlined. I then summarise some of the most recent statistical results on the clustering of galaxies and clusters, using the two-point correlation function xi(s) and the power spectrum P(k). In particular, I concentrate on the increased information available on the detailed shape of these functions on large scales, lambda~100/h Mpc. I argue that significant evidence is accumulating from different observations that P(k) has a well-defined and possibly narrow peak around k~0.05 h/Mpc. I conclude with a glimpse into the future of large-scale structure surveys at high redshifts, describing the features of the VIRMOS deep survey, which will soon start collecting redshifts with the ESO VLT for ~150,000 galaxies at a typical depth of z=1.