black hole
Black holes and galaxies tend to grow in correlation… Not this oneBenny Trakhtenbrot

An ancient black hole has defied the general rule of black holes by outpacing the growth of the galaxy surrounding it.

Scientists had believed the growth of a black hole and the surrounding stars are in direct correlation.

"This is true for the local universe, which merely reflects the situation in the Universe's recent past," says Benny Trakhtenbrot, a researcher at ETH Zurich's Institute for Astronomy. The report, published in Science, states that black holes usually reach a mass of 0.2 to 0.5% of their host galaxy's mass.

However, Trakhtenbrot and colleagues from ETH discovered a giant black hole in a normal sized distant galaxy named CID-947 when using the 10m Keck telescope in Hawaii, which they had utilised in their search for ancient black holes. They found this particular black hole had around 10 times less mass than its surrounding galaxy, making it one of the biggest on record.

"The measurements correspond to the mass of a typical galaxy. We therefore have a gigantic black hole within a normal size galaxy," Trakhtenbrot said.

Nonetheless, the galaxy was still growing with new stars continuing to form whereas the black hole had stopped growing.

"That means this black hole grew much more efficiently than its galaxy – contradicting the models that predicted a hand-in-hand development," Trakhtenbrot added.

Because of how far the light has had to travel, the researchers were studying the black hole when it was just 14% of its current age – at two billion years old.

Black holes are formed when giant stars collapse in on themselves, forming regions from where nothing can escape – not even light. Supermassive black holes can be billions of times the size of our sun.