Enormous new black hole challenges galaxy formation theories


Astronomers have discovered a supersized black hole almost seven billion times as massive as our sun and dozens of times larger than it should be relative to the size of its host galaxy. This was revealed in a new study published Friday in the journal Science.

The discovery, which was made using the WM Keck Observatory in Hawaii, NASA’s Chandra X-ray Observatory, and the European Space Agency’s XMM-Newton spacecraft, could challenge the currently existing models used to explain how galaxies form.

According to Discovery News, lead author Benny Trakhtenbrot, an astrophysicist at the Swiss Federal Institute of Technology in Zurich, and his colleagues have dubbed the black hole CID-947, and said it’s one of the largest phenomenon of its kind ever discovered.

“Our new discovery stands in contrast to what we were expecting to see, based on the ‘common wisdom’ about the relations between supermassive black holes and their host galaxies,” he told redOrbit via email. While many observations in the nearby universe “suggest that there is a tight relation between the masses of black holes and the masses of the galaxies in which they reside,” this system “clearly shows that this is not the general case, particularly in the early universe.”

Black hole that breaks all the rules

CID-947 formed in the early universe about 11.7 billion years ago, or two billion years after the Big Bang, the website added. The presence of extremely fast-moving gas near the supermassive object suggests that it has a very high mass. However, the authors said that they were stunned by the mass of the galaxy surrounding the black hole – it was a fairly normal-sized galaxy.

The average supermassive black hole is approximately 500 timers smaller in mass that its host galaxy, Trakhtenbrot told redOrbit. Based on this observational relation, many models have been proposed to explain the nearly linear relation and the typical ratio. Along with other evidence, this appeared to indicate that supermassive black holes evolve hand-in-hand with their host galaxies, and some studies suggest that they can stop star formation in those galaxies.

CID-947, on the other hand, “has as much as one tenth the mass of its host galaxy – that is, about 50 times higher than what is observed in the local universe,” he explained. Furthermore, the data also suggests that while “the black hole is reaching the final stages of its growth,” the host galaxy is still growing and forming stars. “So, instead of a ‘hand-in-hand’ evolutionary scenario, we are witnessing a ‘two-stage’ case: the black hole grew first, and the host galaxy is growing later.”

Trakhtenbrot has studied this system as part of a larger effort to study growing black holes in the early universe. He said the study “would not have been possible” without the Keck telescope’s MOSFIRE instrument. This equipment is what “allowed us to peer so deeply into the early universe and explore black holes at the final stages of their growth.”


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