Black hole masses and host galaxy properties in distant quasars from reverberation mapping surveys
Powered by accretion onto supermassive black holes (SMBHs), active galactic nuclei (AGNs) and quasars (the most luminous AGNs) are the keys to many outstanding questions in astronomy, including black hole (BH) demographics, BH-host galaxy (co)-evolution, and AGN feedback mechanisms. Reverberation mapping (RM) is the primary technique to measure BH masses beyond the local Universe (z>0.3). RM measures the delay in variability signatures between the accretion disk and the broad-line region (BLR). BH masses can be estimated by combining the BLR radius (inferred from the time delay) and the BLR velocity dispersion (measured from the broad-line width) under the virial assumption. The Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project is one of the first large-scale RM campaigns to simultaneously monitor 849 uniformly selected quasars over a broad luminosity (i-mag<21.7) and redshift (0.1<z<4.5) range, which significantly expands the AGN parameter space for which RM has been conducted. The first part of this dissertation (Chapters 2 and 3) focuses on exploring traditional and statistical methods of measuring lags and optimizing lag detections in large-scale RM surveys. Chapter 2 presents a study of composite lags from light curves with no individually-detected lags using the first-year SDSS-RM spectroscopic monitoring data. Chapter 3 consists of a quantitative study of strengths, weaknesses, and systematic biases of three commonly used lag-measuring techniques under different survey designs. The SDSS-RM program has successfully measured BH masses for around 150 quasars over the past few years. With robust BH mass measurements, these quasars are the premium sample to study the general quasar population, e.g., mass function, scaling relations. The second part of this dissertation (Chapters 4 and 5) presents the first statistical studies on the host galaxy properties (stellar luminosity, stellar mass, and color) and their connections to BH masses of SDSS-RM quasars with RM-based BH masses using imaging data from the Hubble Space Telescope. This work paves the way for measuring RM-based BH masses and studying BH-host relations in ongoing and upcoming industrial-scale RM programs.
Galaxy evolution, Reverberation mapping, Black hole physics, Quasars
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign