Near-infrared AO imaging of QSO host galaxies

We report NIR (primarily H-band) AO imaging with the Gemini-N and Subaru telescopes, of 32 nearby (z < 0.3) QSOs selected from the Palomar-Green bright quasar survey (PGBQS), in order to investigate the properties of the host galaxies. Two-dimensional modeling and visual inspection of the images shows that ∼36% of the hosts are ellipticals, ∼39% contain a prominent disk component, and ∼25% are of undetermined type. Thirty percent show obvious signs of disturbance. The mean MH(host) = −24.82 (2.1LH*), with a range −23.5 to −26.5. At 2LH* most are ellipticals. “Disturbed” hosts are found at all MH(host). Hosts with prominent disks have less luminous QSOs, while the most luminous QSOs are almost exclusively in ellipticals or in mergers (which presumably shortly will be ellipticals). There is a strong correlation between the “infrared-excess”, LIR/LBB, of QSOs with host type and degree of disturbance. Disturbed and strongly disturbed hosts and hosts with dominant disks have LIR/LBB twice that of non-disturbed and elliptical hosts, respectively.