LOS ANGELES - Combining data gathered by NASA's Chandra X-ray Observatory with radio observations and computer simulations, an international team of scientists has found a gigantic X-ray "Tsunami" rolling through the Perseus galaxy cluster, a new study indicates.

Spanning about 200,000 light-years, the wave of hot gas, likely formed billions of years ago, is about twice the size of the Milky Way galaxy, according to a paper to be published in the June 2017 issue of the journal Monthly Notices of the Royal Astronomical Society.

"Perseus is one of the most massive nearby clusters and the brightest one in X-rays, so Chandra data provide us with unparalleled detail," lead scientist Stephen Walker, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.

"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." said Walker.

Galaxy clusters are the largest structures bound by gravity in the universe today. Most of the observable matter within galaxy clusters takes the form of superheated gas, averaging tens of millions of degrees, that only glows in X-rays, according to the US space agency NASA.

Observations by NASA's Chandra X-ray Observatory and other instruments have revealed a variety of structures in Perseus' glowing 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."