Supermassive black holes may create the largest 'tsunamis' in the universe

Astrophysicists have found that the gas escaping a supermassive black hole’s gravitational pull can form tsunami-like structures, as seen in this artist's rendering. (Nima Abkenar/NASA)

Toronto — When an earthquake happens underwater on Earth, it can create a tsunami - a ripple effect of gigantic proportions.

Now, a new study says that out in space, supermassive black holes may create tsunami-like structures.

The NASA-funded study was published on June 15 in the Astrophysical Journal. Researchers used computer simulations to model the environment of a supermassive black hole and found that tsunami-like structures​ can form through gas escaping the black hole’s gravitational pull.

NASA says these structures may be the largest tsunami-like structures in the universe.

A supermassive black hole has a mass that is greater than the mass of a million suns, and is considered the largest category of black holes. These black holes feed off matter and gases that swirl around them, forming a system that astrophysicists call the “active galactic nucleus.”

Strong winds driven by X-ray radiation from the centre of the nucleus create what astrophysics call an “outflow,” pushing matter out of the centre. Within the outflow, the X-rays can produce gas clouds around the black hole.

Illustration by Nima Abkenar

“These clouds are ten times hotter than the surface of the Sun and moving at the speed of the solar wind, so they are rather exotic objects that you would not want an airplane to fly through,” said lead author Tim Waters in a news release from NASA.

During the simulations, Waters and his team have found that these clouds can form into waves as the black hole loses grip on the matter. These waves can further spiral into vortex structures that are 10 light-years away from the black hole as they interact with hot winds, NASA says.

The simulations also shows that X-ray from the plasma near the black hole inflates pockets of heated gas within the black hole’s atmosphere, allowing the hot plasma to rise like a balloon and meet the surrounding cooler gas clouds.

This allows the clouds to form a pattern that astrophysicists call a Kármán vortex street, resembling a tsunami structure.

Previous theories have suggested that the clouds form spontaneously through fluid instability or that magnetic fields were involved in propelling cooler gas into the wind.

“While it all makes sense in hindsight, it was initially quite confusing to observe that thermal instability cannot produce cold gas directly, yet it can take the place of magnetic fields by lifting cold gas into the wind,” said Waters.

NASA says these findings have yet to be observed by satellites, but plasma near active galactic nuclei within these black holes have been observed by observatories on Earth at temperatures and speeds consistent with the simulations.​