‘Supermassive’ black holes aren’t as big as we thought, scientists say

If the thought of a supermassive black hole terrifies you, a new study may provide some relief.  

Scientists say that these galactic giants might not actually be as big as we thought.

Researchers from the University of Southampton used a powerful new tool to measure the black hole at the core of an infant galaxy 12 billion light–years from Earth.

Their analysis revealed that this ‘supermassive’ black hole is actually 10 times smaller than expected.

The scientists say that earlier methods for measuring black holes haven’t been accurately predicting the mass of these colossal voids.

That could mean scientists have overestimated the size of the biggest black holes in the universe for years.

‘Our results suggest the methods to weigh these black holes used previously are just not working reliably in the early universe,’ said co–author Professor Seb Hoenig.

‘It could lead to a re–evaluation of our models of cosmic evolution.’

Black holes are objects formed by the collapse of dying stars, so dense that not even light can escape their gravitational pull.

Scientists believe that supermassive black holes – black holes with a mass at least 100,000 times greater than the sun – formed very soon after the Big Bang.

Over the billions of years that followed, these early black holes grew to enormous sizes by feeding on gases and eventually gathered entire galaxies in their vast orbits.

However, scientists have struggled to understand how supermassive black holes grew to be so large so quickly.

Professor Hoenig says: ‘We have been wondering for years how it’s possible we discovered all these fully grown supermassive black holes in very young galaxies shortly after the Big Bang.

‘They shouldn’t have had the time to grow that massive.’

In a new study, published in the journal Astronomy and Astrophysics, Professor Hoenig and his co–authors argue that the answer is surprisingly simple: supermassive black holes aren’t actually that big.

To reach this conclusion, the researchers focused on an ancient quasar – a black hole so distant and bright that it shines like a beacon from the dawn of the universe.

They measured this ancient light with a powerful new instrument called GRAVITY+.

Co–author Dr Taro Shimizu, of the Max–Planck Institute for Extraterrestrial Physics, told Daily Mail: ‘GRAVITY+ combines the light from the four big telescopes on Paranal Observatory, which mimics the ability of a giant 100–meter telescope and allows for very precise measurements of the motion of the fast gas right near the supermassive black hole.

‘By knowing both the location and speed of the gas, we can then exactly “weigh” the black hole.’

This new analysis revealed that the black hole was 800 million times the mass of the sun – which is still enormous, but 10 times smaller than the researchers had expected.

That huge difference suggests that the methods astronomers use to ‘weigh’ huge objects in space don’t work reliably for these kinds of very old black holes.

Co–author Dr Richard Davies, also of the Max–Planck Institute for Extraterrestrial Physics, told Daily Mail: ‘The previous estimates were based on locally measured relationships which might not work in the early universe.’

Dr Davies says the researchers still aren’t sure why this is the case, but it could be because the black holes are giving out a lot more light than expected.

In addition to revealing the black hole’s weight, the swirling gases in the galaxy’s core also showed that this cosmic void was consuming gas at a rate much faster than had been thought possible.

That feeding frenzy is creating a huge outflow of gas, blasting out into space in a column travelling at speeds of 6,200 miles per second (10,000 km/s).

The researchers think that the intense radiation created by that outflow could have tricked telescopes into thinking the black hole was a lot bigger than in reality.

If other supermassive black holes in the early universe are also smaller than previously expected, it could have big consequences for our theories about the development of the universe.

Dr Davies adds: ‘This is very significant, especially for understanding how galaxies and black holes grow and evolve.’