The Hosts of Ultraluminous Infrared Galaxies

Abstract

Complete samples of ultraluminous infrared galaxies have been imaged at R-band and K-band from Mauna Kea. Here we present a preliminary analysis of the host galaxy magnitudes and the 1-D radial profiles for a subset of objects in the IRAS 1-Jy sample of ULIGs (z < 0.3), and compare these properties with recently published data for "low-z" QSOs. ULIGs in the 1-Jy sample reside in luminous hosts, with mean luminosities 2.7L* at K-band (range 0.7-11 L*) and 2.2L* at R-band (range 0.5-9 L*), values that are remarkably similar in the mean and range for the hosts of low-z QSOs. Approximately one-third of ULIGs have single nuclei and radial profiles that are closely approximated by a r{1/4}-law over the inner 2-10 kpc galactocentric radius. These "E-like" hosts have half-light radii, and surface brightness similar to QSO hosts at R-band, but systematically smaller half-light radii than QSOs at K-band.