Supermassive black holes feed off gas clouds across galaxies

A new research by an international team of scientists has uncovered the process by which supermassive black holes (SMBHs) - gigantic black holes with masses millions of times greater than our sun - feed off gas clouds which reach them by travelling hundreds of thousands of light years from one galaxy to another.

Using data from the 4-metre Anglo-Australian telescope in New South Wales, Australia, the team led by Dr Sandra Raimundo, an astrophysicist and lead researcher from the University of Southampton to study, studied the orbits of gas and stars in a large sample of more than 3000 galaxies.

The team, which also includes researchers from the universities of Copenhagen and California, identified those with the presence of what is known as ‘misaligned’ gas - gas which rotates in a different direction from the stars in the galaxy - which is an indication of a past galaxy interaction, had a higher proportion of active supermassive black holes.

The results indicated a strong connection between misaligned gas and the activity of supermassive black holes, implying that the gas is transported when two galaxies come together, travels a long way through space, and then is drawn in and consumed by the immense gravitational force of the supermassive black hole as a necessary energy source. Astronomers have long thought that a merger with another galaxy could be the source of this gas, but there has been no direct proof of this.

"The work that we carried out shows the presence of gas that is misaligned from stars is associated with an increase in the fraction of active supermassive black holes. Since misaligned gas is a clear sign of a past interaction between two galaxies, our work shows that galaxy interactions provide fuel to power active supermassive black holes," Dr Raimundo said.

The researchers are now looking to expand their study and use their discoveries to figure out what proportion of the total mass of supermassive black holes was generated by this process and how significant it was in the early Universe.

Their findings are published in the journal Nature Astronomy.