Institute for Advanced Study Informal Astrophysics Seminar

ABSTRACT: The correlation between the masses of central supermassive black holes (SMBHs) and the bulge luminosity of their host galaxies ---the SMBH-bulge relation--- is seen as fundamental to understand the formation and (co-)evolution of SMBHs and galaxies, as well as to predict SMBH masses at high(er) redshifts. With the aim to refine and extend the SMBH-bulge relation, we obtained very deep and high-resolution near-infrared images of 35 galaxies with secure stellar dynamically measured SMBH masses. After performing in-depth image decompositions, we not only find ambiguities in the definition and hence also inferred luminosities of the bulges, but also that the SMBH masses correlate equally well with the total luminosity of galaxies. Moreover, while the slope of the BH-bulge relation varies when selecting subsets of different types of galaxies, the one-to-one relation with total luminosity is robust. In an other ongoing effort, we have obtained long-slit spectra of well over 600 nearby galaxies for which the resulting combination of stellar velocity dispersion and (redshift) distance allows us to predict the SMBH sphere-of-influence. Next, we plan to request for expensive follow-up high-spatial resolution spectroscopy for those with sphere-of-influences large enough to dynamically measure the SMBH mass. In the meantime, we found 6 compact galaxies with half-light radii of only~2 kpc, disk-like rotation and in particular very high dispersions reaching 400 km/s in their centers. The availability of HST imaging for one of the six allowed us to construct Schwarzschild orbit-based dynamical models that require a 17+/-3 billion solar mass SMBH to fit the data, while the total stellar mass of the galaxy is only 120 billion solar masses. This SMBH-to-total mass fraction of 12% is at least two orders of magnitude higher than expected from the SMBH-bulge relation. If the other compact galaxies host similar uebermassiv SMBHs, it would be another indication that the BH-bulge relation is not fundamental.