A group of Columbia astronomers found a pair of supermassive black holes that are only one light-week apart, which means that they may soon collide into one another. Scientists explained that these black holes are almost one thousand times closer to each other than any other black holes we have knowledge of.
The duo was detected 3.5 billion light years away in the Virgo constellation. When they collide, astronomers estimate that the ripple effects would temporary disturb the space-time fabric as Albert Einstein forecasted several decades ago.
Scientists can observe the gravitational waves predicted by the famed physicist only when two supermassive black holes manage to merge. Although such collisions result in a tremendous energy output, astronomers can rarely witness such event when it is about to occur.
The Columbia team admitted that they resorted to an optical trick to detect the two merging black holes. Zoltan Haiman, lead author of the discovery, explained that despite popular belief supermassive black holes are not frozen into one spot for eternity. They are moving and they can get close to one another and eventually collide.
The newly found technique that allowed astronomers spot the unusual pair could help them detect even more black holes that are about to merge or are in the midst of a collision.
Supermassive black holes hold a tremendous gravitational pull. They are so dense that not even light can escape their gravitation. Almost every galaxy has such black hole at its core, and galaxies also collide, forcing their black holes into one another until they form a binary pair. As time goes by, black holes in the pair will get even closer and one of them will cannibalize the other.
Scientist can observe these binary pairs with help from quasars generated by merging galaxies. Quasars look very much like lighthouses that emit their beacon of light at regular intervals. The light in fact is emitted by a very active black hole that burns through cosmic material. Binary quasars emit their light even more often when the pair of black holes is about to merge.
Study authors studied a quasar named PG 1302-102, which was know to increase its brightness by 14 percent every five years. Scientist knew that this quasar signaled that there was a pair of gravitationally locked black holes less than 1/10 of a light year apart from one another. Next, researchers applied the doppler effect to verify whether there was a shift in the space objects’ brightness as they circle one another. The team noted that PG 1302-102 displayed a change in UV light spectra every five years.
As a follow-up, the team plans to use the method on 100 more quasars and maybe witness a pair of black holes collide.
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