Astronomy Colloquium - Misty Bentz

Comparing Direct Black Hole Mass Measurements in AGNs

Supermassive black holes seem to be ubiquitous in galaxy nuclei, and several large-scale galaxy properties have been found to scale with black hole mass, giving rise to the idea that galaxies and their black holes co-evolve.  There are only a few techniques that can directly constrain the mass of a black hole through its gravitational influence on luminous matter, of which the most commonly used are reverberation mapping and stellar or gas dynamical modeling.  These techniques have been applied to a modest number of black holes, with the vast majority of black hole masses in the literature instead being estimates derived from scaling relationships that are based on direct mass measurements.  To date, there are only a handful of black holes with masses that have been constrained through multiple techniques because of the disparate technical requirements.  In AGNs, the situation is even worse because active galaxies are rare and most are too far away to allow the spatial resolution needed for dynamical modeling.  I will describe our ongoing project to directly compare black hole masses from reverberation mapping and stellar dynamical modeling in the nearest active galaxies, including our upcoming JWST Early Release Science program.  Both reverberation mapping and stellar dynamical modeling are time- and resource-intensive techniques and the number of galaxies we can study with both techniques is small, but the results will help uncover potential biases in these direct mass techniques and illuminate any differences in the black hole mass scales that are applied locally versus at cosmological distances.

Speaker: Misty Bentz, Georgia State University

Image Description and Credit: Artist’s illustration of an active galactic nucleus shrouded by gas and dust. Do such sources help or hurt the formation and survival of life in a galaxy? [NASA/JPL-Caltech]