200,000 light-year-wide tsunami of hot gas spotted in Perseus galaxy

3 May 2017

Image: Dmitriy Rybin/Shutterstock

Astronomers have observed a giant tsunami of hot gas within the nearby Perseus galaxy cluster, which spans an incredible 200,000 light years.

The near incomprehensible size of space has been highlighted once again, following observations made by a team of international astronomers in the nearby Perseus galaxy cluster.

By using combined data from NASA’s Chandra X-ray Observatory with radio observations and computer simulations, the team published findings detailing a giant tsunami wave of hot gas.

The Perseus galaxy cluster is one of the largest objects in the universe, measuring 11m light years and located 240m light years away.

Believed to have formed billions of years ago when a small galaxy grazed Perseus, the tsunami wave spans a staggering 200,000 light years. The gas contains a variety of structures, most notably the concave feature known as the ‘bay’.

To come to this conclusion, the researchers ruled out the possibility of the cluster’s central supermassive black hole being the instigator, as the bay’s concave shape couldn’t have formed through bubbles launched by the black hole.

It was then a matter of comparing the imagery the team had collated with all of the available imagery and data, before passing it through NASA’s Pleiades supercomputer to run a number of simulations.

This x-ray image of the hot gas in the Perseus galaxy cluster was made from 16 days of Chandra observations. The first is Chandra’s best view of hot gas in the central region of the Perseus cluster, where red, green and blue indicate lower-energy to higher-energy x-rays, respectively. Image: NASA’s Goddard Space Flight Center/Stephen Walker et al

Similar features in other galaxies

One result in particular suggested that gas in a large cluster similar to Perseus had settled into two components. The first central region is dubbed the colder region because it was ‘only’ 54m degrees Celsius, surrounded by another zone of gas that was three times hotter than this.

It was then that a small galaxy cluster – about a thousand times the mass of the Milky Way – skirted the larger cluster, missing its centre by around 650,000 light years.

The resulting grazing of the two galaxies created a spiralling of cold gas from the first region, which rose after 2.5bn years, nearly 500,000 light years from its centre.

The resulting gas cloud we see today is made up of Kelvin-Helmholtz waves, which show up wherever there’s a velocity difference across the interface of two fluids, like wind blowing over water.

“We think the bay feature we see in Perseus is part of a Kelvin-Helmholtz wave, perhaps the largest one yet identified, that formed in much the same way as the simulation shows,” said lead scientist Stephen Walker.

“We have also identified similar features in two other galaxy clusters, Centaurus and Abell 1795.”

Colm Gorey was a senior journalist with Silicon Republic