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The Demography of Super-massive Black Holes

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[*] The demography of super-massive black holes
van der Marel R.P.
in the Space Telescope Science Institute Annual Report, p. 14, 2000
© 2001. Association of Universities for Research in Astronomy. All Rights Reserved.


Super-massive black holes in the centers of galaxies are some of the most enigmatic objects in the Universe. In active galaxies and quasars their appetite for matter provides us with a stunning display of fireworks, including X-ray emission, radio jets, and rapidly moving gas clouds. In normal galaxies, starved of fuel, they lurk quiescently.

The Hubble Space Telescope has revolutionized our knowledge of these super-massive black holes. By measuring the motions of stars and gas in the centers of galaxies, Hubble has not only proven their existence but also directly determined their masses. The Space Telescope Imaging Spectrograph (STIS) is particularly well suited for such studies. STIS is now allowing us to address the demography of the super-massive black hole population.

Illustration A special session entitled `Supermassive Black Hole Research and Advances with STIS' at the American Astronomical Society meeting in Rochester drew together astronomers to discuss newly emerging results. Earlier reports were confirmed that supermassive black holes may well exist in all galaxies, and that the black-hole mass correlates loosely with the mass of the galaxy bulge. In addition, two groups independently reported a strong correlation between the mass of the black hole in a galaxy and the magnitude of the random motions of its stars.

These results provide new insight into the origin of supermassive black holes. One plausible scenario is that galaxies and their black holes form simultaneously in an phase that manifests itself through strong quasar activity. This is quantitatively consistent with the statistics of quasars in the distant Universe and with the statistics of black holes in the nearby Universe.

In the coming years, further studies of super-massive black holes using STIS will undoubtedly bring a clearer understanding of the origin and demographics of these remarkable objects.


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Last modified April 6, 2001.
Roeland van der Marel, marel@stsci.edu.
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