|10-21-2008, 01:11 AM||#1|
Avalon Senior Member
Join Date: Oct 2008
Giant Black Holes Destined for Cosmic Collision
The sharpest image yet of a very distant, early galaxy has revealed that it's really two galaxies harboring whopping black holes that are fighting over food.
One of the fraternal twin galaxies is prolifically birthing new stars while the other appears to be stealing gas and dust away from its sibling. Eventually, the two must merge, along with their black holes.
The light from galaxy 4C60.07 has traveled to Earth from 12 billion years ago -- a time within just two billion years of the Big Bang, say astronomers who used the powerful Submillimeter Array radio telescope in Hawaii to zero in on the objects.
Unlike more familiar radio telescopes, the Submillimeter Array looks at higher-frequency radio waves that are best detected at high elevations.
In these higher frequencies, emissions from carbon monoxide (CO) gas can be seen from across the universe. The telescope also has very high angular resolution, meaning it can discern very small patches of the sky.
By comparing the Submillimeter Array data with that of the same galaxy pair made by the Spitzer infrared space telescope, the surprising sibling rivalry was discovered.
"One of them has CO, and then there is another (CO emission) that's in the middle of nowhere," explained Steve Wellner of the Harvard-Smithsonian Center for Astrophysics. The one with CO is pumping out scads of new stars, he said. The other is not.
The CO gas in the space between the galaxies is being ripped away from the more prolific twin by the more sterile galaxy.
A report of the discovery co-authored by Wellner appears in the latest issue of the Monthly Notices of the Royal Astronomical Society.
"This has been an ongoing mystery for years," said Kenney of the absence of young stars in elliptical galaxies, which also happen to be the largest galaxies in the universe.
The faint streamers of hydrogen gas between the two galaxies were previously detected at the edges of images of both galaxies M86 and NGC4438, but it wasn't until new technologies enabled a wider, deeper view of the space between them that the connection was discovered, said astronomer Bill Keel of the University of Alabama.
"These galaxies have a history," concluded Keel. The discovery underscores the growing realization that no galaxy is an island, he said. "It's no longer an isolated, stable system." It's part of a larger process of collisions, mergers and near misses.
Keel said he is hoping Kenney and his colleagues will search for more telltale gas filaments between other galaxies in the Virgo cluster, where both M86 and NGC 4438 reside. M86 is the brightest galaxy in the Virgo cluster, a neighbor galaxy cluster about 50 million light-years away from our own Local Group cluster.
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