New view of quasars sheds light on origin.Quasars Proper naming of quasars are by Catalogue Entry, Qxxxx±yy using B1950 coordinates, or QSO Jxxxx±yyyy using J2000 coordinates.
This page lists quasars.
Viewed through Earth's atmosphere, the blinding light of a quasar quasar (kwā`sär), one of a class of blue celestial objects having the appearance of stars when viewed through a telescope and currently believed to be the most distant and most luminous objects in the universe; the name is shortened from appears as a fuzzy blob, obscuring its much fainter galactic living quarters. The sharp eye of the Hubble Space Telescope Hubble Space Telescope (HST), the first large optical orbiting observatory. Built from 1978 to 1990 at a cost of $1.5 billion, the HST (named for astronomer E. P. Hubble) was expected to provide the clearest view yet obtained of the universe. , however, can pick out the cores of galaxies that quasars call home. Two independent Hubble surveys now reveal that of 35 observed galaxies that host quasars, about half appear to have been ripped apart, to have suffered recent collisions, or to be about to merge with a nearby galaxy.
These violent scenes suggest that many quasars light up when a collision or merger creates a fresh supply of gas and dust, reviving a dormant black hole at the center of a galaxy. The black hole embarks on a feeding frenzy, sucking in the new material. As the gas and dust spiral in, they radiate away much of their energy, generating the quasar's fierce emissions.
Until the Hubble mug shots, astronomers had little evidence for this widely held view about the origin of quasars, says Hubble astronomer Michael Disney of the University of Wales Affiliated institutions
The universe was more compact in the past because less time had elapsed e·lapse
intr.v. e·lapsed, e·laps·ing, e·laps·es
To slip by; pass: Weeks elapsed before we could start renovating.
n. since the Big Bang big bang
Model of the origin of the universe, which holds that it emerged from a state of extremely high temperature and density in an explosive expansion 10 billion–15 billion years ago. triggered its expansion, he notes. As a result, collisions and mergers between galaxies were more frequent, and the chances of rejuvenating a dormant black hole were considerably higher. To sustain a quasar, a black hole must continually refuel re·fu·el
v. re·fu·eled also re·fu·elled, re·fu·el·ing also re·fu·el·ling, re·fu·els also re·fu·els
To supply again with fuel.
v.intr. . This suggests that quasars have short lives-perhaps 100 million years-and that many galaxies today harbor quiescent black holes, Disney says.
Some nearby galaxies whose cores are bright, but less luminous than quasars, could contain the embers of quasars that ran out of fuel, comments Harley A. Thronson of NASA NASA: see National Aeronautics and Space Administration.
in full National Aeronautics and Space Administration
Independent U.S. headquarters in Washington, D.C.
Using Hubble's wide-field and planetary camera, Disney and his European collaborators found that 11 of the 20 host galaxies they observed show evidence of having been disrupted or being about to collide with another galaxy. Similarly, a team led by John N. Bahcall John Norris Bahcall (December 30 1934 – August 17 2005) was an American astrophysicist. He is best known for his contributions to the solar neutrino problem and the development of the Hubble Space Telescope, and for his leadership and development of the Institute for Advanced of the Institute for Advanced Study in Princeton, N.J., used the camera to examine another 15 galaxies that harbor quasars. The researchers found that nearly half show signs of recent disturbance. Disney and Bahcall reported their findings at a press briefing in Washington, D.C.
Bahcall says the images show that a surprising variety of galaxies, some of which appear to be completely isolated, host quasars. Disney counters that at least some of these seemingly isolated bodies may have eaten a galaxy too small for Hubble to discern. Bruce H. Margon of the University of Washington in Seattle estimates that a galactic black hole needs to devour only a few times the mass of the sun in gas and dust each year to fuel a quasar.