The Gemini Echo Mapping Project

Measuring the mass of the supermassive black holes (SMBHs) found at the center of nearly every massive galaxy is essential to our understanding of the cosmic evolution of these exotic objects in the Universe. However, at great cosmological distances, it is extremely challenging to measure SMBH masses. A primary technique, called "reverberation mapping" (or echo mapping), is to measure the light echo from the brightness flickering of the accretion flow around the SMBH and the response of the gas cloud emission further out. When combined with the speed of these clouds, a black hole mass can be derived as these clouds are moving under the gravitational influence of the black hole. This project will measure the masses of a sample of distant SMBHs with reverberation mapping and advance our understanding of their accretion processes. The program includes related educational opportunities and public outreach activities. This project (Gemini Echo Mapping — GEM) will obtain cadenced, multi-year, optical spectroscopy from the two Gemini telescopes for a sample of twelve accreting SMBHs across a wide range of cosmological distances (from redshift of 0.2 to about redshift 2). Combining intensive monitoring data from other ground-based facilities, in particular, the multi-epoch spectra from the Sloan Digital Sky Survey, GEM is promising to enable accurate measurements of the masses of these SMBHs by resolving the detailed velocity structure of the gas clouds echoing the luminosity flickering in the vicinity of the black hole. GEM will allow accurate measurements of black hole masses and a systematic investigation of the structure and kinematics of the gas clouds around accreting SMBHs. GEM will also establish a pathway to developing robust recipes of mass estimation for SMBHs across cosmic time. 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.