The Hosts of Z = 2 Qsos

We present results of the hosts of four high-redshift (z 2) and high luminosity (M B < ?28 mag) QSOs, three radio-quiet one radio-loud, imaged in R and K bands. The extensions to the nuclear unresolved source are most likely due to the hosts galaxies of these QSOs. The luminosities and sizes of the hosts overlap with those of actively star-forming galaxies in the nearby Universe. Radial prooles over the outer resolved areas roughly follow de Vaucouleur or exponential disk laws. These properties give support to the host galaxy interpretation of the extended light around QSOs at high-redshift. If the hosts we have detected are indeed galaxies, young massive and luminous galaxies are not only a characteristic of radio-loud QSOs, but of QSOs as an entire class. 1 Introduction The study of high redshift (z 2) QSOs ooers a unique opportunity to investigate conditions in the early universe. In the currently favoured cold dark matter cosmogony, this epoch corresponds to the period when normal galaxies formed through hierarchical coalescence 3], thereby giving rise to enormous concentrations of gas in the center of the galaxies, which could feed a central black hole 7] or provoke a massive starburst episode 12]. As such, this picture is consistent with the observation that the QSO population peaks at these redshifts 10]. Searches for galaxies hosting high-redshift QSOs were rst carried out in radio-loud objects, with spectacular results: luminosities several magnitudes brighter than the most luminous galaxies in the nearby Universe were observed 8]. However, radio-loud quasars are only a small fraction (< 1%) of all QSOs, and many of the conclusions drawn from radio-loud objects