Sloan Digital Sky Survey | 2018 Jan 09
Today, astronomers from the Sloan Digital Sky Survey (SDSS) announced new measurements of the masses of a large sample of supermassive black holes far beyond the local Universe.The results, being presented at the American Astronomical Society (AAS) meeting in National Harbor, Maryland and published in the Astrophysical Journal, represent a major step forward in our ability to measure supermassive black hole masses in large numbers of distant quasars and galaxies. ...
- An artist’s rendering of the inner regions of an active galaxy/quasar, with a supermassive black hole at the center surrounded by a disk of hot material falling in. The inset at the bottom right shows how the brightness of light coming from the two different regions changes with time. Credit: Nahks Tr’Ehnl and Catherine Grier (Penn State Univ) and the SDSS collaboration
Supermassive Black Holes (SMBHs) are found in the centers of nearly every large galaxy, including those in the farthest reaches of the Universe. The gravitational attraction of these supermassive black holes is so great that nearby dust and gas in the host galaxy is inexorably drawn in. The infalling material heats up to such high temperatures that it glows brightly enough to be seen all the way across the Universe. These bright disks of hot gas are known as “quasars,” and they are clear indicators of the presence of supermassive black holes. By studying these quasars, we learn not only about SMBHs, but also about the distant galaxies that they live in. But to do all of this requires measurements of the properties of the SMBHs, most importantly their masses.
The problem is that measuring the masses of SMBHs is a daunting task. Astronomers measure SMBH masses in nearby galaxies by observing groups of stars and gas near the galaxy center — however, these techniques do not work for more distant galaxies, because they are so far away that telescopes cannot resolve their centers. Direct SMBH mass measurements in galaxies farther away are made using a technique called “reverberation mapping.” ...
The Sloan Digital Sky Survey Reverberation Mapping Project: Hα and Hβ
Reverberation Measurements from First-year Spectroscopy and Photometry - C. J. Grier et al