Giant black holes
Astronomers Plan to Capture Image of Black Hole NASA

Using the Chandra X-ray Observatory, NASA astronomers have discovered a new pair of supermassive black holes lying in close proximity to the Milky Way galaxy.

The two black holes were discovered in a spiral galaxy codenamed NGC 3393. The close proximity of the galaxy indicates that the black holes lie as little as 160 million light years from Earth, making them the nearest known pair ever discovered.

The two are believed to be separated by just 490 light years and are thought to be the remnant of a merger between two different, unequally sized galaxies that occurred more than a billion years ago.

The revelation breaks from NASA scientists' previous belief that a single supermassive black hole lay at the centre of NGC 3393. The reappraisal occurred after "a long look," NASA researchers discovered two locations growing and emitting X-rays.

NASA scientists say the existence of the two black holes in NGC 3393 is atypical of science's current understanding of black holes' effects on galaxies. According to NASA, NGC 3393 is still a "well-organized spiral galaxy" with a central bulge still "dominated by old stars."

Researchers speculate that the two black holes combined with the oddities of the galaxy's makeup could show NGC 3393 to be the first known instance of a merger occurring between a large galaxy and a much smaller one.

"The two galaxies have merged without a trace of the earlier collision, apart from the two black holes," commented Junfeng Wang of the Center for Astrophysics. "If there were a mismatch in size between the two galaxies it wouldn't be a surprise for the bigger one to survive unscathed."

"Collisions and mergers are one of the most important ways for galaxies and black holes to grow," commented Guido Risaliti of CfA and the National Institute for Astrophysics in Florence, Italy. "Finding a black hole pair in a spiral galaxy is an important clue in our quest to learn how this happens."

NASA said its researchers had not yet had a chance to fully examine all the data taken by the Chandra X-ray Observatory and that it would release further news about NGC 3393 as it became available.