Research

My research focus is on Active Galactic Nuclei (AGN) and Supermassive Black Hole (SMBH) growth.  Gas clouds that are deep within the potential well of an active SMBH emit photoionization lines, Doppler-broadened by several 1,000 km/s.  Measuring the size and velocity dispersion of this broad line region (BLR) provides a way to infer the mass of the SMBH.  However, the distances to most AGN make spatially resolving the BLR very challenging, and much of its structure and dynamics are uncertain.  The variable continuum emission of an AGN produces corresponding responses in the broad lines that are modulated by light travel-time delays. The response is described by the transfer function, which contains information on the physical properties, structure, and kinematics of the BLR.  The reverberation mapping technique, a time-series analysis of the driving light continuum curve and time-delayed response of the broad lines, can recover some of this information.  I have developed a new forward-modeling tool, the Broad Emission Line MApping Code (BELMAC), that simulates the velocity-resolved reverberation response of the BLR to an observed input light curve, given the bolometric luminosity and spectral energy distribution of the AGN.  It is the first reverberation mapping code to incorporate photoionization models to enable modeling of ultraviolet, optical, and near infrared broad lines.  It is a unique tool for interpreting the BLR reverberation and single-epoch spectroscopy data from intensive time-domain campaigns as well as large-scale surveys.