2011AJ....141..141M

We have obtained high spatial resolution Keck OSIRIS integral field spectroscopy of four z ∼ 1.5 ultra-luminous infrared galaxies that exhibit broad Hα emission lines indicative of strong active galactic nucleus (AGN) activity. The observations were made with the Keck laser guide star adaptive optics system giving a spatial resolution of 0".1 or <1 kpc at these redshifts. These high spatial resolution observations help to spatially separate the extended narrow-line regions–possibly powered by star formation–from the nuclear regions, which may be powered by both star formation and AGN activity. There is no evidence for extended, rotating gas disks in these four galaxies. Assuming dust correction factors as high as A(Hα) = 4.8 mag, the observations suggest lower limits on the black hole masses of (1-9)x10⁸ M_☉ and star formation rates <100 M_☉/yr. The black hole masses and star formation rates of the sample galaxies appear low in comparison to other high-z galaxies with similar host luminosities. We explore possible explanations for these observations, including host galaxy fading, black hole growth, and the shut down of star formation.