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Our systematic HI survey of early-type galaxies has revealed several objects with large, regular disks of neutral hydrogen of up to 200 kpc in size. Given their size and regular kinematics these disks must be quite old, in many cases well over 5 × 10 yr. They may represent key structures that trace the origin and evolution of these galaxies.

Future deep galaxy surveys will cover a range in redshift over which the galaxy-bias and density field evolve significantly. In this brief conference proceedings contribution, we describe how models for these effects can be factored into a clustering analysis and can then be constrained by the data. Even for recent low-redshift surveys such as the 2dF galaxy redshift survey (2dFGRS), luminosity-dependent galaxy-bias can change the recovered clustering signal from that of the underlying density field [5].

We investigate the relation between the central velocity dispersion, , and the circular velocity, , in galaxies, which could be interpreted as a relation between the masses of central black holes and dark matter halos. We consider an observationally homogeneous sample of 52 high surface brightness (HSB) spiral galaxies and 11 low surface brightness (LSB) spiral galaxies in addition to HSB literature data. We performed a straight line regression analysis in a linear scale, finding a good fit, also for low galaxies, always rejected in the previous studies. LSB galaxies, for the first time considered for this purpose, seem to behave differently, showing either higher values of or lower values of with respect to their HSB counterparts.

Solid observational evidences indicate a strong dependence of the galaxy formation and evolution on the environment. In order to study in particular the interaction between the intracluster medium and the evolution of cluster galaxies, we have created a large database of clusters of galaxies based on the largest available X-ray and optical surveys: the ROSAT All Sky Survey (RASS), and the Sloan Digital Sky Survey (SDSS). We analyzed the correlation between the total optical and the X-ray cluster luminosity. The resulting correlation of and shows a logarithmic slope of 0.6, a value close to the self-similar correlation. We analysed also the cluster mass to light ratio, by finding a significant dependence of / on the cluster mass with a logarithmic slope ranging from 0.27 in the i and r bands to 0.22 in the z band.

Deep 1.4 GHz counts show an upturn below a few milliJansky (mJy), corresponding to a more rapid increase in the number of faint sources. This change of slope is thought to be due to the emergence of a new population of radio sources, which does not show up at higher flux densities. Today we know that the faint radio population is a mixture of different classes of objects (AGNs, star-forming galaxies, normal ellipticals and spirals), but the relative fractions are still uncertain and very little is known about the luminosity properties and the redshift distribution of such sources. Understanding whether the dominant triggering process is star formation or nuclear activity has important implications on the study of the star-formation/black-hole-accretion history with radio-selected samples.

The VIRMOS preparatory imaging survey (Le Fèvre et al. 2003) was designed to provide a photometric coverage in the bands of one deep and three wide areas to be be observed with VIMOS. The -band data for the deep and one wide area are here presented.

Understanding the links between the formation and evolution of the AGN population and the formation and evolution of galaxies requires investigation of the relationship between these populations at high redshift, where the quasar luminosity function is reaching a maximum. We have made a deep space-based near-infrared (NIR) imaging study of the properties of the host galaxies of  ~ 2–3 radio-quiet quasar (RQQ) hosts and compared them to those of the other known high- galaxies, the Lyman break galaxies (LBGs) and the hosts of radio-loud objects. We found that the RQQ hosts have rest-frame optical magnitudes and sizes that are similar to the LBGs, and are much fainter than most radio-loud hosts at these epochs. We have also obtained rest-frame ultraviolet (UV) imaging of this sample, and use this to study the UV–optical colors of the hosts. These allow us to compare the star-forming properties of the quasar hosts with those of the LBGs.

Stellar masses of galaxies are derived from the -band (2.2 m) photometry by taking into account evolution and cosmological effects with the code PÉGASE. The evolution scenarios are robust: they give reference spectra for valid photometric redshifts and fit the deepest galaxy counts with the standard cosmological model. Baryonic masses of the progenitor gaseous clouds are then derived. The baryonic maximum value  = 10 M fits the radio galaxy - sequence from  = 0 to 4. Since this cut value is observed at all in the Hubble diagram, it favors a physical origin: i.e., the fragmentation limit of 10 M predicted by Rees & Ostriker, 1977. One consequence is the discovery of high mass (≃ 10 M) galaxies at  ≥ 4, constraining the mass accumulation time-scales (Rocca-Volmerange et al. 2003).

X-ray selected EROs are, on average, the hardest X-ray sources in medium and deep X-ray fields. This coupled with their extremely red colors (R-K > 5) suggest that they represent one of the most promising population where looking for high-luminosity (L > 10 erg s) and X-ray obscured (N > 10 cm) type2 AGNs, the so called QSO2 (e.g., [5]; [4]; Mignoli et al. submitted to A&A). These latter are predicted in large density by the synthesis model of the Cosmic X-ray background [9] even if only few observational evidences have been found so far (e.g., [1] and references therein; Caccianiga et al. A&A accepted).

The Subaru/XMM-Newton Deep Survey[1] (SXDS) comprises deep optical and X-ray observations of an area of sky larger than a square degree. With a transverse size of 100 Mpc at  = 1.5, the SXDS can detect and measure large-scale structure which will strongly affect the global results from smaller surveys. This region of sky is also home to a 0.8-deg ultra-deep near-infrared imaging survey [2], a 0.25-deg submillimetre survey [3], and also lies within the XMM-LSS region which will be observed by SIRTF as part of the SWIRE Legacy Program [4], and by GALEX as part of its Deep Imaging Survey and Medium–Deep Spectroscopic Survey. Extragalactic radio sources are able to probe large-scale structure and inform on the accretion and star formation histories of the Universe, and we have therefore undertaken deep radio observations to complete an unparalleled multi-wavelength dataset. This paper introduces the radio data in this field.