UC Irvine

This dissertation presents the results of a set of research projects focused on using optical and near-infrared Hubble Space Telescope and CO(2-1) Atacama Large Millimeter/submillimeter observations to measure the masses of central black holes in nearby (< 100 Mpc) early-type galaxies. By modeling the rotation of circumnuclear disks, I dynamically measured the masses of eight supermassive black holes in the following galaxies: NGC 1380, NGC 6861, NGC 4786, NGC 5193, NGC 3245, NGC 4435, NGC 5838, and ESO 208-G21.

I developed a thin disk gas-dynamical modeling framework in Python in order to analyze, model, and interpret the observed ALMA CO(2-1) gas kinematics. Using near-infrared (J and H-band) Hubble Space Telescope data from Wide Field Camera 3, I constructed Multi-Gaussian Expansion models in GALFIT to model the gravitational potential of the host galaxy and developed a novel method to account for the effects of circumnuclear dust on molecular gas-dynamical black hole mass measurements using two-band color information. I performed rigorous systematic and statistical tests of my dynamical models to fully explore the error budget of each measurement. Key limiting factors on the precision of mass measurements such as dust extinction, recent star-formation, low level active galactic nuclei activity, insufficient angular resolution, and lack of dynamical information within the black hole's sphere of influence were identified.

In summary, I provide the following black hole mass measurements and estimates for the eight early-type galaxies: NGC 1380 (102-204 million solar masses), NGC 6861 (1.13-2.89 billion solar masses), NGC 4786 (370-640 million solar masses), NGC 5193 (130-290 million solar masses), NGC 3245 (90-140 million solar masses), NGC 4435 (50-80 million solar masses), NGC 5838 (1 million - 1.94 billion solar masses), and ESO 208-G21 (230 million solar masses) The mass measurements of the central black holes in NGC 1380, NGC 4786, NGC 5193, NGC 5838, and ESO 208-G21 are the first black hole mass measurements of any kind in those galaxies, while the NGC 3245, NGC 4435, and NGC 6861 mass measurements provide independent crosschecks of previous results.