WASHINGTON, D.C.--The latest pictures from the Hubble Space Telescope, unveiled here today at NASA headquarters, reveal that the enigmatic cosmic lighthouses known as quasars reside in many more kinds of galaxies than scientists had previously thought.
Astronomers John Bahcall of the Institute for Advanced Study in Princeton, New Jersey, and Michael Disney of the University of Wales in Cardiff have imaged 34 nearby quasars and their stellar neighborhoods, providing the clearest view yet of the mysterious objects that produce more light than trillions of suns combined. The images confirm that quasars exist not as lonely beacons but as components of a wide variety of galaxies: regular spirals, regular ellipticals, and many irregular galaxies undergoing collisions or other distortions.
A primary reason for building the space telescope, says Disney, was to get a better look at quasars, which have long puzzled scientists with their concentrated, bright light. Ground-based observations had hinted that they exist as part of galaxies, but the quasars are so bright that they obscure their relatively dim surroundings. And Earth's atmosphere distorts the view even more. The new images, taken from the unencumbered vantage point of space, are a "big step forward," Bahcall says. "We now have clear pictures of the homes and environments of quasars."
More controversial, however, is whether the images shed light on how quasars form. According to Bahcall, "We do not have a simple picture--we have a mess." Disney disagrees. He claims to see evidence for galactic collisions surrounding 11 of the 15 quasars his group imaged. Because such collisions are relatively rare, Disney says, this suggests they have something to do with quasar formation.