Luminous Quasars in Luminous Early-Type Host Galaxies

Some recent observations of nearby quasars with HST have apparently failed todetect host galaxies. We review the HST observations as well as near infraredground-based observations of the same objects. We find that the quasar hostscan be detected in the HST data if they are smoothed sufficiently to reveal lowsurface brightness. The smooth hosts are very difficult to detect with HST butare more easily visible in the deeper, ground-based IR images. The V-H colorsobtained by combining the HST and IR data are compatible with normal galaxycolors at the redshifts of the quasars. This behavior can be explained if thehosts are massive early-type galaxies. All together, HST images have beenreported for 15 luminous quasars, approximately 13 of which have smoothearly-type hosts. This kind of galaxy therefore appears to be the most commonhost for a luminous quasar.Comment: Accepted to ApJLett, 10 pages uuencoded gzipped PostScript (includes 2 figures) plus a grey-scale image in the same forma