Astronomers have caught the first definitive glimpse of one of the most dramatic events in the universe. Billions of light-years away, two galaxies are merging into one, creating a supermassive binary quasar at their center.
Quasar is the term given to the central regions of extremely distant, ancient galaxies. The supermassive black holes at the center of these galaxies accrete huge amounts of matter, which in turn gives off massive amounts of energy and light. Because quasars can be seen from such colossal distances - the nearest ones are at least three billion light-years from Earth - they are considered the most luminous, energetic objects in the universe. Although they do not look particularly bright from Earth, the fact that they can be seen at all from such a distance means they must necessarily be incredibly luminous.
Because galaxies tend to be grouped together, they interact on a regular basis, which often leads to mergers. Scientists had hypothesized that these mergers are what create quasars, because the upheaval of smashing two galaxies together causes the supermassive black holes to begin the accretion of matter. This would mean that quasars are really binary quasars, as they are powered by the pair of black holes at the merging galaxy's cores.
This theory was unconfirmed, however, because the galaxies in question were too distant to observe with sufficient resolution. However, the recently observed object SDSS J1254+0846 appears to fit the bill. John Mulcahey of the Carnegie Institution explains the find:
"Just because you see two galaxies that are close to each other in the sky doesn't mean they are merging," says Mulchaey. "But from the Magellan images we can actually see tidal tails, one from each galaxy, which suggests that the galaxies are in fact interacting and are in the process of merging."
Further computer simulations appear to confirm the observations of Mulcahey and others. Galactic mergers do indeed appear to be the engines of quasar formation. It looks like those dull little lights in the far corner of the sky are really the aftereffects of just about the most cataclysmic events imaginable.
[Via Science Daily]