Penn State Astronomers Discover Well-Established Black Holes in Distant Quasars

An international team of scientists led by Penn State Associate Professor of Astronomy and Astrophysics Niel Brandt has used NASA's Chandra X-Ray Observatory to detect the three most distant known quasars, among the most luminous objects in the Universe. The team's observations with Chandra recorded high-energy X-ray emissions that were produced more than 10 billion years ago by the quasars' massive black holes.

The discovery that these quasars are prodigious producers of X-rays indicates the supermassive black holes powering them were already in place when the Universe was only about one billion years old. "Chandra's superb sensitivity has allowed the detection of X-rays from the dawn of the modern Universe, when the first massive black holes and galaxies were forming," Brandt says. "These results indicate that future X-ray surveys should be able to detect the first black holes to form in the Universe."

The three quasars were recently discovered at optical wavelengths by the Sloan Digital Sky Survey--a large international effort that aims to observe 100,000 quasars, measure the distances to a million galaxies, and produce a comprehensive digital map of the sky. The three quasars are 13-billion light years from Earth, making them the most distant known quasars. Brandt's team includes Penn State Professor of Astronomy and Astrophysics Donald Schneider, who has been chair of the Sloan Digital Sky Survey Quasar Science Group since its inception in the early 1990s and has set many previous records for the discovery of "most distant" quasars, Penn State Postdoctoral Scholar Gordon Richards, and many scientists from the Sloan survey.

"Since X-rays reveal conditions in the immediate vicinity of supermassive black holes, we proposed last year that Chandra look at these objects to see if they are different from their older counterparts," said Schneider. The proposed observations, performed on January 29, 2002, were made public immediately and other astronomy teams quickly went to work on them, including teams led by Daniel Schwartz of the Harvard-Smithsonian Center for Astrophysics, Smita Mathur of Ohio State University, and Jill Bechtold of the University of Arizona. Brandt's team concluded that the quasars looked similar to ones that were at least twice as old, so the conditions around the central black hole had not changed much in that time, contrary to some theoretical expectations.

All groups agreed that the masses of the black holes producing the X-rays are enormous, given their relative youth. By various estimates, the three quasars each have masses between one and 10 billion times the mass of the Sun. By comparison, the black hole at the center of the Milky Way is believed to contain the mass equivalent to only about 3 million Suns.

The results of Brandt et al. have been published in the Astrophysical Journal Letters (Brandt et al. 2002, ApJL, 569, L5). The results of Mathur et al. and Schwartz will appear in separate papers to be published in the Astrophysical Journal Letters; the work of Bechtold et al. will be published in the Astrophysical Journal.

The observations were made with Chandra's Advanced CCD Imaging Spectrometer, which was conceived and developed for NASA by Penn State and the Massachusetts Institute of Technology under the leadership of Gordon Garmire, Evan Pugh Professor of Astronomy and Astrophysics at Penn State. Commenting on this most recent discovery with the detector whose development he led, Garmire said, "I am delighted that our X-ray detector on Chandra has proven to be such a fine tool for pushing our vision further and further back in time and space toward the first generation of objects to form in the Universe."

The observations of the three quasars detected in this study are part of an extensive effort at Penn State to investigate the earliest sources of X-ray emission in the Universe. Previous work, which was led by Penn State Postdoctoral Scholars Cristian Vignali and Shai Kaspi, has produced published papers on the discovery of X-ray emission from 21 very distant quasars. Currently, Penn State astronomers including Brandt, Schneider, Garmire, Vignali, and Richards are in the process of preparing 10 additional X-ray discoveries for publication and are scheduled to make several additional observations of distant quasars with Chandra in during the coming year.

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program, and TRW, Inc., Redondo Beach, California, is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Massachusetts.

CONTACT:

Niel Brandt: 814-865-3509, niel@astro.psu.edu

Donald Schneider: 814-863-4682, dps@astro.psu.edu

Barbara Kennedy (PIO): 814-863-4682, science@psu.edu

IMAGES:

http://chandra.harvard.edu

http://chandra.nasa.gov

MORE INFORMATION ABOUT THE QUASARS:

In addition to SDSS 1306+0356, which has a cosmological redshift z = 5.99, the other distant Sloan Digital Sky Survey quasars observed in this study are SDSS 0836+0054 (redshift z = 5.82) and SDSS 1030+0524 (redshift z = 6.28).

Information on the original discovery of these quasars, including an optical image, optical spectra, and other relevant information is on the web at <http://www.sdss.org/news/releases/20010605.edr.html>.

More information about the Sloan Digital Sky Survey is on the web at <http://www.sdss.org>.