The most distant radio galaxies and the formation of massive galaxies.

In this paper we discuss some recent observations of distant (2 < z < 4.5) radio galaxies including, (i) submillimetre dust emission measurements as carried out with SCUBA, (ii) HST imaging to probe the spatial distribution of the stars and (iii) deep ROSAT imaging to probe hot cluster gas. Subsequently, we briefly present a sample of extremely steep spectrum radio sources from the WENSS, NVSS and FIRST radio surveys which are currently our best candidates for z > 5 radio galaxies. Our recent deep K-band imaging indicates that these objects might indeed be at these extreme distances.

Finally, we discuss these observations in the context of models of galaxy formation. It seems that a simple interpretation of the observations is that (i) a massive burst of starformation in a number of clumps distributed over a spatial scale of 50 kpc and (ii) the subsequent merging of these starforming clumps with the central object are both important processes in the formation of these galaxies. Furthermore, the observations seem to indicate that these distant radio galaxies are the precursors of present day brightest clusters galaxies.