COSMIC EVOLUTION OF BLACK HOLES AND SPHEROIDS. IV. THE MBH-Lsph RELATION

From high-resolution images of 23 Seyfert-1 galaxies at z = 0.36 and z = 0.57 obtained with the Near-Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope (HST), we determine host-galaxy morphology, nuclear luminosity, total host-galaxy luminosity, and spheroid luminosity. Keck spectroscopy is used to estimate black hole mass (M-BH). We study the cosmic evolution of the M-BH-spheroid luminosity (L-sph) relation. In combination with our previous work, totaling 40 Seyfert-1 galaxies, the covered range in BH mass is substantially increased, allowing us to determine for the first time intrinsic scatter and correct evolutionary trends for selection effects. We re-analyze archival HST images of 19 local reverberation-mapped active galaxies to match the procedure adopted at intermediate redshift. Correcting spheroid luminosity for passive luminosity evolution and taking into account selection effects, we determine that at fixed present-day V-band spheroid luminosity, M-BH/L-sph proportional to (1 + z)(2.8 +/- 1.2). When including a sample of 44 quasars out to z = 4.5 taken from the literature, with luminosity and BH mass corrected to a self-consistent calibration, we extend the BH mass range to over 2 orders of magnitude, resulting in M-BH/L-sph proportional to (1 + z)(1.4 +/- 0.2). The intrinsic scatter of the relation, assumed constant with redshift, is 0.3 +/- 0.1 dex (<0.6 dex at 95% CL). The evolutionary trend suggests that BH growth precedes spheroid assembly. Interestingly, the M-BH-total-host-galaxy-luminosity relation is apparently non-evolving. It hints at either a more fundamental relation or that the spheroid grows by a redistribution of stars. However, the high-z sample does not follow this relation, indicating that major mergers may play the dominant role in growing spheroids above z similar or equal to 1.