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We investigate correlations between the location of galaxies in dense environments and their degree of star-formation activity. Using photometric redshifts and spectral classifications from the COMBO-17 survey [1] we are able to precisely isolate galaxies from a 4 × 4  Mpc region around the Abell 901/902 supercluster in the range 0.15 <  < 0.18. We measure rest-frame photometric quantities from PEGASE template fits to the 17-band photometric data, and divide supercluster galaxies into two classes (‘quiescent’ and ‘star-forming’) based on deviation blueward of the ( – ) vs. colour-magnitude sequence.

Using the MPIfR Max Planck Millimeter Bolometer array (MAMBO) on the IRAM 30m Telescope we have mapped the ELAIS N2 and Lockman Hole East Fields at 1200 m to a rms noise level of 0.8–1.0 mJy per 11 beam. The areas surveyed are 326 arcmin in the ELAIS N2 field and 212 arcmin in the Lockman Hole, and cover the 260 arcmin previously observed by SCUBA [5].

A catalogue of galaxies with extremely red colours (R-J≥5), covering 8.43 square degrees has been selected from optical and near-infrared data. Based on their bright near-infrared magnitude and their very red colour, these objects are likely to be very massive galaxies with little or no ongoing star formation. We have derived a surface density of 0.0396 ± 0.0011 arcmin (Poisson uncertainties) for these Extremely Red Objects.

The TexOx 1000 (TOOT) radio source redshift survey [1] is designed to find and study radio-loud active galaxies to high redshift. They are typical in the same sense that L galaxies are typical of galaxies in the optical. Previous surveys have only included the most luminous, rare objects at and beyond the peak of activity at z ~ 2, but in going a factor of 100 fainter than the 3C survey, and in assembling a large sample, TOOT probes for the first time the objects that dominate the radio luminosity density of the universe at high redshift.

We report deep submm mapping of 7 high-redshift radio galaxies (HzRGs). These data confirm not only the presence of spatially extended massive star-formation activity in the radio galaxies themselves, but also in companion objects previously undetected at any wavelength. The prevalence, orientation, and inferred masses of these companion galaxies suggest that we are witnessing the synchronous formation of the most luminous elliptical galaxies found today at the centres of rich galaxy clusters.

In this contribution we highlight a large programme that is being undertaken to establish the physical links between black-hole mass, host galaxy properties and cluster environments of a sample of radio galaxies spanning ~ 3 dex in radio luminosity at a single cosmic epoch. The sample of 41 radio galaxies is drawn from four complete radio samples and is comprised of all narrow-line radio galaxies in the redshift range 0.4 <  < 0.6. This allows us to delineate the effects of cosmic evolution from genuine radio-power dependent characteristics.

We are carrying out a search for Ly emitting galaxies at  = 6.5 employing slitless spectroscopy at the VLT. In our 43 arcmin field we find three isolated single emission lines with SEDs consistent with line emitting galaxies at  = 6.5.

By means of high-resolution N-body simulations in a CDM cosmology, we verify that scaling relations similar to those observed for nearby galaxy clusters are also defined by their dark matter hosts; the slopes, however, are not the same. We then show that the scaling relations of galaxy clusters can be explained as the result of the cosmological collapse of density fluctuations at the appropriate scales, plus a systematic trend of the / ratio with cluster mass. The empirical fact that the exponent of the Faber-Jackson relation of elliptical galaxies is significantly different (higher) than that of clusters, force us to conclude that the galaxy scaling laws might derive from the cosmological collapse of density fluctuations at the epoch when galactic scales became non-linear, plus modifications afterward due to early-time dissipative merging.

Objects with unusual red near-IR color J-K > 3 are extremely rare at magnitude brighter than K=20, while their surface density increases at fainter magnitudes. The nature of these sources has not yet been firmly established even if all the analysis performed so far conclude that they are galaxies at z > 2-3 ([1], [2], [3]). A detailed analysis based on a multi-band data set (from 0.3 m to 2.15 m) of three J-K > 3 sources selected at Ks < 22 on the HDF-S ([4]) has shown that: i) the three galaxies are at redshift 2.5 < z < 3; ii) they have a stellar mass content of M~ 10M; iii) they would populate the bright end (L ~ L) of the local luminosity function of galaxies even assuming they evolve passively; iv) they cannot follow an evolution significantly different from passive aging.

We have observed a sample of 19 Very Luminous Infrared Galaxies (VLIRGs, [8–1000m] 10 < L < 10) with the Nordic Optical Telescope (NOT) + Andalusia Faint Object Spectrograph and Camera (ALFOSC) on La Palma, in B and I-bands. We discuss here the results of measuring preliminary morphological Concentration, Asymmetry, and Clumpiness (CAS) parameters for these galaxies. The results show VLIRGs as having similar Concentration to ULIRGs, but the Asymmetry and Clumpiness values show a considerably wider dispersion, which is unexpected. We are reanalyzing these preliminary results to assess their reliability.