Its existence has been long theorized

Mar 5, 2009 07:16 GMT  ·  By
An artist depicts how a black hole, formed from one of the stars in a binary system, attracts the other one to its core, consuming it
   An artist depicts how a black hole, formed from one of the stars in a binary system, attracts the other one to its core, consuming it

Since astronomers first discovered galactic mergers, theorists have argued that one of the results of such a merger would be the creation of a binary black hole system, much similar to a binary star system. Thus far, their quest for one has proven futile, but now an extensive study from the Sloan Digital Sky Survey team may have just found the elusive galactic formation. The find is detailed in the March 5th issue of the scientific journal Nature.

Binary star systems are made of two nearly identical stars orbiting the same center of gravity, or by one larger celestial body, and a smaller one, the latter orbiting the first. As far as galaxies go, when two of them collide, they exchange nearly all matter they have with each other, in a process that ends up in a merger, over millions of years. And since all galaxies have black holes at their cores, it would make sense that, eventually, the two come together.

However, what happens in such a circumstance has been a subject for debate. While some say that the two formations would begin orbiting each other, just like stars do, others argue that the larger black hole would simply absorb the smaller one, thus creating a supermassive one and giving birth to numerous interesting cosmic effects, such as rare particle emissions and the likes.

The recent study, which has observed light emitted by roughly 17,500 quasars, seems to favor the first hypothesis. “The black holes orbit each other in a small tightly bound orbit, unable to lose enough momentum so that they could actually merge,” National Optical Astronomy Observatory (NOAO) study team member Tod Lauer, who is currently working from the facility's headquarters, in Tucson, Arizona, explains.

According to the theory, the black holes cannot merge on account of the gravitational momentum they still hold from moving away from their former galaxies. In order for them to be able to unite, astrophysicists share that the accumulation of gas in their immediate vicinity is absolutely necessary. Large amounts of gas might just absorb enough of the formations' momentum, in order to push them against each other.

When this happens, theorists continue by saying, we might be able to observe the emissions of gravitational waves that the new Laser Interferometer Space Array (LISA) instrument, currently under development, could possibly discover. The search for these waves is ongoing, but their reading may be so faint that not even the most powerful human-built observers could be able to detect them. It remains to be seen if the black holes Lauer has discovered will, indeed, form a binary system. Still, the process will be complete in a few million years, so only simulations are in order at this time.