In the fifty years since the discovery of quasars, a picture of these enigmatic objects has emerged wherein quasars are supermassive black holes residing at the centers of large galaxies. The black hole may have a mass of millions to billions times that of the sun. As this picture implies, the quasar phenomenon is one and the same as that of the objects referred to as "active galactic nuclei." All are characterized by enormous luminosity such that the quasar frequently outshines the light from all of the billions of stars in its host galaxy. The existence of black holes has captivated people of all levels of scientific sophistication. The study of active galactic nuclei as well as the nucleus of our own galaxy has produced strong evidence that, indeed, supermassive black holes do exist and that they are the engines at the heart of the quasar phenomenon. This project aims to continue the estimate of the mass of the supermassive black holes in a sample of objects and extend it to objects of higher luminosity than those previously studied via a combination of an intense observational program as well as development of new analysis techniques.
This collaborative project will establish the state of the art in "reverberation mapping" of active galaxies and quasars. Reverberation mapping is a technique where one looks at the reaction of the emission line spectrum of the active object to see how it responds to a change in the intensity of the continuum source that ionizes and excites the surrounding line-emitting gas. It is a technique that has been employed over the last few decades to measure the size and structure of the so-called broad line region in active galactic nuclei, and, in the past five years, the technique has been applied to high-cadence observations to provide the best constraints on the mass of the accreting black hole at the heart of the active object. This project will further advance the technique via a three-phase effort: (1) analysis of data from a high-cadence optical/ultraviolet monitoring campaign for NGC 5548 that will represent the single most intensive reverberation mapping program ever attempted; (2) execution of a one year duration reverberation mapping campaign at Lick Observatory to probe broad-line region structure at luminosities an order of magnitude higher than the luminosities probed by other recent dedicated monitoring programs; and (3) new development of state-of-the-art software for modeling reverberation mapping data. The combination of these projects will make it possible to dissect the structural and dynamical properties of the broad-line region in greater detail than ever before, enabling critical new tests of the local calibration for the quasar black hole mass scale.
