Disk Evolution sincez ∼ 1 in a CDM Universe

Increasingly large populations of disk galaxies are now being observed atincreasingly high redshifts, providing new constraints on our knowledge of howsuch galaxies evolve. Are these observations consistent with a cosmology inwhich structures form hierarchically? To probe this question, we employSPH/N-body galaxy scale simulations of late-type galaxies. We examine theevolution of these simulated disk galaxies from redshift 1 to 0, looking at themass-size and luminosity-size relations, and the thickness parameter, definedas the ratio of scale-height to scale-length. The structural parameters of oursimulated disks settle down quickly, and after redshift z=1 the galaxies evolveto become only slightly flatter. Our present day simulated galaxies are larger,more massive, less bright, and redder than at z=1. The inside-out nature of thegrowth of our simulated galaxies reduces, and perhaps eliminates, expectationsof evolution in the size-mass relation.Comment: accepted version, to appear in ApJ 01 March 2006, v63