Researchers have used data from NASA’s Chandra X-ray Observatory and some other telescopes in order to put up a detailed map of a rare collision between four galaxy clusters. All four clusters will eventually merge to become one of the biggest objects in our Universe. Each cluster has a mass of at least hundred trillion times that of the Sun.
For those of you who don’t know, Galaxy clusters are the largest objects from the cosmos, which are held together thanks to gravity. They have thousands of galaxies kept together in hot gas, and they also appear with large amounts of invisible dark matter. Sometimes, two galaxy clusters collide – see the Bullet Cluster case – and sometimes even more than two can collide at the same time.
These new observations suggest that a mega-structure is assembled in a system that’s called Abell 1758, which is placed about 3 billion light-years from Earth. It has two pairs of colliding galaxy clusters, which are moving towards one another. Researchers found out about Abell 1758 as being a quadruple galaxy cluster system back in 2004. For this, they used data from Chandra and XMM-Newton, a satellite operated by ESA – European Space Agency.
Each and every pair from the system comes with two galaxy clusters that are on their way to merging. In one of the pairs, the centers of every cluster have already passed each other once, and that happened 300 to 400 million years ago. They will eventually go back around.
The Chandra data first revealed a shock wave, which was similar to the sonic boom from a supersonic aircraft. The shock wave was found in hot gas, which was visible to Chandra in the collision of the northern pair.