/Grad Student Discovers Shock Wave in Merging Galaxy Clusters, Confirms a Missing Link

Grad Student Discovers Shock Wave in Merging Galaxy Clusters, Confirms a Missing Link

Key idea: Arnab Sarkar, a graduate student in the University of Kentucky Department of Physics and Astronomy, will reveal data and images that — for the first time — confirm the existence of a shock wave created between two galaxy clusters early in the merging process.

Original author and publication date: University of Kentucky June 16, 2022

Futurizonte Editor’s Note: Much to learn about the universe, both outside and inside ourselves (same universe, by the way).

From the article:

The findings will be presented today during the American Astronomical Society’s (AAS) semiannual meeting, taking place in Pasadena, California this week.

Galaxy clusters are the most massive, gravitationally bound systems in the universe. When two galaxy clusters collide, theories predict that their first contact would create a shock wave between them. For the first time, Sarkar and his team detected such an axial shock between two clusters that are about to merge. 

Sarkar, who is also a predoctoral scholar with the Center of Astrophysics | Harvard & Smithsonian, says this is a very important confirmation in understanding the assembly of structures in the universe.

“With this discovery, we caught two sub-clusters of a galaxy cluster in a crucial early epoch of the merging process, with a strong shock between them, providing a missing link to the formation of the most massive structures in our universe,” he said.

The shock was detected using the Chandra X-Ray Observatory, in a galaxy cluster known as Abell 98, which lies more than 1,200 million light-years away from Earth. The strong shock wave Sarkar and his team detected travels at a speed of 4.5 million miles an hour between two sub-clusters, which is 20,000 times faster than the fastest Formula 1 cars.

Sarkar notes that catching galaxy clusters early in the merging process is very rare. Because they are millions of light years apart from each other. The axial shock waves predicted by the theory at the initial phase of their merger were never observed before. Detection of such a shock in an early- stage merging cluster was, therefore, a long-standing missing piece of the puzzle of galaxy cluster formation.

“This result is important because different computer simulations seem to be telling us different things about what we should observe early on in a galaxy cluster merger,” Sarkar said. “Here, we have a picture of what this process actually looks like, and that can be used to inform our theoretical models.”

READ the full article