NASA Chandra X-ray Observatory Spots Colossus in Coma Cluster of Galaxies

NASA's Chandra X-ray Observatory has helped make another surprising discovery. It's spotted the enormous arms of hot gas in the Coma cluster of galaxies. Spanning at least half a million light years, these features reveal how the Coma cluster has grown through mergers of smaller groups and clusters of galaxies to become one of the largest structures in the universe held together by gravity.

Coma is an unusual galaxy cluster. It has not one, but two giant elliptical galaxies near its center. These two giant elliptical galaxies are probably vestiges from each of the two largest clusters that merged with Coma in the past. In fact, the new data reveals signs of past collisions and other mergers.

The two massive arms were probably formed when smaller galaxies had their gas stripped away from them by the head wind created by the motion of the cluster through the hot gas. Think of the headwind that's created by a roller coaster, which can blow hats off of the people on the ride.

So what did the researchers find out about this system? The X-ray emission that the instruments captured is from multimillion degree gas. The optical data, in contrast, reveals galaxies in the Coma Cluster, which contain only about one-sixth the mass in hot gas. The X-ray arms themselves are estimated to be about 300 million years old and appear to have a rather smooth shape. This new finding, in turns, gives researchers some more clues about the hot gas in Coma.

Researchers expected that mergers between clusters like those in Coma would produce strong turbulence. Yet that's obviously not the case. The smooth shape of the X-ray arms points to a rather calm setting for the hot gas in the Coma cluster, even after many mergers. It's possible that large-scale magnetic fields are responsible for this small amount of turbulence.

The findings reveal a little bit more about this massive structure. This, in turn, could help scientists with future findings. The new data allows them to better understand just how these mergers come to be and could help with future insight into other structures.

The findings are published in the journal Science.