Irish team helps solve cosmic black hole riddle, opening new area of research

24 Jan 2019

Zoomed image of the inner 30 light years of a dark matter halo. The rotating gaseous disc breaks apart into three clumps that collapse under their own gravity to form supermassive stars. Image: John Wise/Georgia Institute of Technology

DCU researchers collaborated with astronomers from the US to solve a black hole mystery that has plagued them for years.

Due to the intensity of the light released from the first black holes at the birth of the universe, astronomers here on Earth are able to observe them in great detail. However, one of the biggest mysteries has been how these enormous black holes came to be.

The new findings published to Nature by a team including Dublin City University (DCU), three US universities, the San Diego Supercomputer Center and IBM showed that when galaxies assemble extremely rapidly, and sometimes violently, it can lead to the formation of a massive black hole.

Instead of the normal formation of stars, the rapidly assembling gas results in embryonic stars being puffed up, leading to the formation of a so-called supermassive star. These stars only survive for a very short time before collapsing in on themselves in dramatic fashion to form a massive black hole.

This contradicts the long-accepted belief that massive black hole formation could only happen in regions bombarded by powerful radiation from nearby galaxies.

Next steps

Dr John Regan of DCU, an author of the study, said this discovery opens a whole new area of research in astronomy.

“At first when we found these black hole formation sites in the simulation, we were stumped. As we delved deeper we saw that these sites were undergoing a period of extremely rapid growth – that was the key!” he said.

“Our next goal is to probe the further evolution of these exotic objects. Where are these black holes today? Can we detect evidence of them in the local universe or with gravitational waves?”

This discovery was something of a major achievement considering the scale at which the universe works, requiring some serious technological firepower.

Prof Turlough Downes, director of the Centre for Astrophysics and Relativity at DCU and another author of the study, explained: “The ‘Renaissance simulations’ of the early universe, on which this research is based, achieve this by working out ‘on the fly’ where interesting things are happening and focusing a lot of effort there.

“However, even with this extremely efficient method, this work is so challenging that there is no way to get these unique insights into our universe without the use of some of the world’s largest supercomputers.”

Colm Gorey was a senior journalist with Silicon Republic