You can't have a galaxy without a black hole
UNIVERSITY OF MICHIGAN NEWS RELEASE
Posted: February 19, 2001
Galaxies and black holes are so intimately connected that it is almost impossible to find one without the other, according to University of Michigan astronomer Douglas Richstone. Over the last decade, Richstone and a team of researchers have detected massive black holes in all but one of the 30 spiral galaxies they surveyed.
"The mass of these objects appears to correlate with the mass of the central part of their host galaxy," said Richstone, a U-M professor of astronomy. "Radiation and high-energy particles released by the formation and growth of black holes are the dominant sources of heat and kinetic energy for star-forming gas in protogalaxies. Black holes and stars compete for baryons, or particles of matter, that form stars during the early life of galaxies."
Comparisons of the history of star formation in the universe with the history of quasars, conducted by other scientists, reveal that quasars developed well before most star formation in galaxies. Quasars are extremely powerful bright objects capable of generating the luminosity of one trillion suns within a region the size of Mars' orbit.
"The massive black holes we now see in centers of galaxies are relics of these quasars," Richstone explained. "So black holes must have already been present at the height of the quasar epoch when the universe was about one billion years old."
"The energy output of a massive black hole is comparable to the energy of the galaxy over its entire lifetime," Richstone said. "Black holes and stars compete for mass, and black holes heavily influence the thermodynamics of the interstellar gas in young galaxies. So it is impossible to sensibly discuss the galaxy formation process, or the history of star formation, without including the formation of black holes."
Other astronomers on Richstone's black hole research team include: Ralf Bender of the Ludwig Maximillian University in Munich; Gary Bower, Richard Green and Tod Lauer of National Optical Astronomy Observatories; Alan Dressler and Luis Ho of Carnegie Observatories; Sandra Faber of the University of California-Santa Cruz; Alex Filippenko of the University of California-Berkeley; Karl Gebhardt of the University of Texas; Carl Grillmair of SIRTF Science Center; John Magorrian of the University of Durham, United Kingdom; Jason Pinkney of the University of Michigan; and Scott Tremaine of Princeton University.
Research funding was provided by NASA and the Space Telescope Science Institute.