California Institute of Technology
Election Year: 1978
Primary Section: 12, Astronomy
Membership Type: Foreign Associate
My current research is centered on the distribution of quasars in the Universe. Quasars are the most luminous known objects. They reside at the centers of galaxies and obtain their brilliance from the accretion of matter onto a massive black hole. Quasars can be observed to distances in excess of 10 billion light years. As a consequence of such long light travel times, we explore earlier stages of the Universe in observing more distant quasars. As we look backwards in time, the number of quasars increases sharply, by a factor of about 100, and then at yet larger distances declines. The peak in quasar numbers, at about 20 percent of the present age of the Universe, probably signifies the birth of galaxies and of big black holes in the early Universe.