Collaborative Research: Establishing the foundations of black hole mass measurements of AGN across cosmic time

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Part 1 Supermassive black holes are the largest black holes in the universe, ranging from millions to billions of times the mass of the Sun. A major theme in astronomy is understanding how these black holes grew to their enormous masses. This project will investigate the growth of black holes by carrying out observational studies of quasars, which are supermassive black holes that are growing rapidly. Using a method called "echo mapping", the investigators will determine how gas flows around the black holes in quasars and measure the masses of the black holes. This work will use new data analysis tools and software developed by their team that will make it possible to measure the black hole masses with higher accuracy than earlier methods. They will also analyze data from earlier observing projects in order to assemble a large collection of quasars with accurate black hole mass measurements. They will use these results to develop improved methods to estimate the masses of black holes in the most distant quasars in the universe. This work will provide an important new foundation for studies of black hole growth across the history of the cosmos. The investigators will work with undergraduate astronomy majors, focusing on conducting research. They will mentor and advise students considering going on to graduate school, and will provide summer research opportunities to students in the "Cal-Bridge" program. Part 2 Understanding the growth and evolution of supermassive black holes across cosmic time is a central theme in astronomy. Very distant black holes can only be identified and studied when they are actively growing by accreting matter from their surroundings and shining brightly as quasars. Measuring the masses of the black holes in quasars is a key to understanding how black holes grow and influence their environments. The technique of "echo mapping" is one of the best tools to study the physical properties and black hole masses of quasars. This method uses the variations over time in a quasar's light to map out the distribution and motion of gas around the black hole. The goal of this project is to advance the science of quasar echo mapping through a combination of new observations and the development of new data analysis methods. The investigators will acquire new echo mapping data using several telescopes, and use the data to map the distribution of gas around the black holes. They will apply new data analysis methods developed by our team to interpret echo mapping data in a physical framework that will enable direct determination of the masses of black holes. Finally, they will carry out a uniform re-analysis of all available echo mapping data from earlier work, and use the results to derive an improved calibration of the black hole masses in distant quasars. This work will provide a rigorous new foundation for investigations of black hole growth across the history of the universe. The investigators will work with undergraduate astronomy majors, focusing on conducting research. They will mentor and advise students considering going on to graduate school, and will provide summer research opportunities to students in the "Cal-Bridge" program. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.