Active Galactic Nuclei: Masses and Dynamics

In this dissertation, I present the results of work to improve measurements of black hole masses (MBH) and investigate the structure of the broad line region (BLR) in active galactic nuclei (AGNs), which are key tracers of galaxy formation and evolution. I address these issues by carrying out high-cadence reverberation mapping experiments on several targets using the telescopes at MDM Observatory on Kitt Peak and by further testing the relationship between MBH and host-galaxy velocity dispersion (sigma) as a calibrator for the MBH scale.Reverberation mapping can be employed for two specific purposes: 1) Measurement of MBH in AGNs and 2) Determination of BLR dynamics. We obtained improved reverberation measurements of the radius of the BLR and MBH for the object PG 2130+099 and performed a re-analysis of previous data. Reverberation data were also collected at several observatories over a 140-day span in 2010. We obtained high sampling-rate light curves for five objects, from which we have measured the average radius of the H-Beta-emitting region and calculated MBH. Our new measurements substantially improve previous measurements for these objects. We also measure the lag in the He II emission line relative to the optical continuum in Mrk 335, which is the first robust lag measurement for a high-ionization line in a narrow-line Seyfert 1 galaxy.We also recovered velocity-resolved reverberation lags for all five AGNs and velocity-delay maps for four. In all four objects, velocity-delay maps show evidence for gravitational infall and in some cases Keplerian motion. These maps constitute a large increase in the number of objects for which we have resolved velocity-delay maps and provide evidence supporting the reliability of reverberation-based MBH measurements.Finally, I discuss the results of an investigation with the Gemini North 8-m telescope to obtain sigma measurements in high-mass quasars. I report successful measurements for four objects that improve the quality of two measurements near the high-mass end of the distribution and add two new objects to the sample. We update the entire AGN MBH-sigma sample and obtain a new estimate of the virial factor used to calibrate all MBH measurements in AGNs.