Summary: The hosts of z = 2 QSOs
Itziar Aretxaga 1 , B.J. Boyle 2 and Roberto J. Terlevich 3
1 Max­Planck Institut f¨ur Astrophysik, Garching, Germany
2 Anglo­Australian Observatory, Epping, Australia
3 Royal Greenwich Observatory, Cambridge, UK
Abstract
We present results of the hosts of four high­redshift (z ß 2) and high luminosity
(MB ! ¸ \Gamma28 mag) QSOs, three radio­quiet one radio­loud, 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
star­forming galaxies in the nearby Universe. Radial profiles 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 high­redshift. If the
hosts we have detected are indeed galaxies, young massive and luminous galaxies are not
only a characteristic of radio­loud QSOs, but of QSOs as an entire class.
1 Introduction
The study of high redshift (z ß 2) QSOs offers a unique opportunity to investigate conditions
in the early universe. In the currently favoured cold dark matter cosmogony, this epoch corre­
sponds 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

Source: Aretxaga, Itziar - Instituto Nacional de Astrofísica Óptica y Electrónica

Collections: Physics