A team of astroboffins from ETH Zurich's Institute for Astronomy have discovered an enormous black hole that shouldn't exist.

The black hole is one of the largest ever recorded, the equivalent of about seven billion the mass of our Sun. It resides in the heart of galaxy CID-947, which is around 11 billion light years away, meaning it formed within a few billion years of the Big Bang.

"Our survey was designed to observe the average objects, not the exotic ones," said Megan Urry, Yale’s Israel Munson Professor of Astrophysics and co-author of the the paper published in the journal Science. "This project specifically targeted moderate black holes that inhabit typical galaxies today. It was quite a shock to see such a ginormous black hole in such a deep field."

Big black holes aren't new, but they have only been found in enormous galaxies. The prevailing theory is that a hole's growth is linked to its host galaxy's size. Black holes typically account for between 0.25 to 0.5 per cent of a galaxy's mass, but this latest discovery has a mass equal to 10 per cent of CID-947.

"The measurements of CID-947 correspond to the mass of a typical galaxy," said researcher Benny Trakhtenbrot. "We therefore have a gigantic black hole within a normal size galaxy. The result was so surprising, two of the astronomers had to verify the galaxy mass independently. Both came to the same conclusion."

The black hole theory isn't totally blown, however. The team acknowledges that it may be that such black holes could only exist in the early stages of the universe's growth, which is why such massive holes on normal galaxies aren't seen closer to Earth.

One theory is that black holes grew more rapidly in early days post-Big Bang because the smaller size of the universe made it much denser. That material would allow black holes to grow faster than today, but more data is needed to verify the hypothesis. ®