Cosmic Evolution of Quasar Host Galaxies

Using HST WFPC2 and NICMOS observations, and our 2D image weighting and modelling technique (Floyd et al. 2004), we have reliably disentangled host from nucleus for nine optically matched radio-loud quasars (RLQ) and nine radio-quiet quasars (RQQ) at z = 1&2, in two bands spanning the 4000Abreak. The resulting galaxy colours provide the first unbiased estimates of galaxy mass for a statistical sample of quasars at high redshift, and indicates a difference in the evolution of radio-loud and radio-quiet objects.