Giant wave of hot gas discovered in nearby Perseus galaxy cluster
A vast wave of hot gas - believed to be the largest ever identified - has been discovered sweeping through the nearby Perseus galaxy cluster.
Scientists say the wave, spanning some 200,000 light-years, is about twice the size of our own Milky Way galaxy.
The discovery was made by combining data from NASA's Chandra X-ray Observatory with radio observations and computer simulations.
“Perseus is one of the most massive nearby clusters and the brightest one in X-rays, so Chandra data provide us with unparalleled detail,” said lead scientist Stephen Walker at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The wave we've identified is associated with the flyby of a smaller cluster, which shows that the merger activity that produced these giant structures is still ongoing."
Chandra observations have revealed a variety of structures in this gas, from vast bubbles blown by the supermassive black hole in the cluster's central galaxy, NGC 1275, to an enigmatic concave feature known as the bay, as per a NASA release.
The researchers say the wave formed billions of years ago, after a small galaxy cluster grazed Perseus and caused its vast supply of gas to slosh around an enormous volume of space.
As per computer simulations, billions of years ago that gas was settled, but a smaller galaxy flyby caused the gas like cream stirred into coffee, creating an expanding spiral of cold gas. After about 2.5 billion years, when the gas has risen nearly 500,000 light-years from the center, vast waves form and roll at its periphery for hundreds of millions of years before dissipating.
These waves are giant versions of Kelvin-Helmholtz waves, which show up wherever there's a velocity difference across the interface of two fluids, such as 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," Walker said. "We have also identified similar features in two other galaxy clusters, Centaurus and Abell 1795." You can watch the video of the new findings below!