Research

UK Physicist Helps Reveal Galaxy Cluster Traveling on 'Intergalactic Highway'

photo of Chandra X-ray observatory image of galaxy cluster
These images show X-ray data from ESA's XMM-Newton and NASA's Chandra X-ray Observatory, along with optical and infrared data. UK's Yuanyuan Su led the analysis of the Chandra X-ray observation. Photo courtesy of Chandra X-ray observatory.

LEXINGTON, Ky. (July 12, 2021) — An international team of researchers have discovered a galaxy cluster acting like a passenger on what astronomers are calling an "intergalactic highway."

The cluster is known as the "Northern Clump" and is located about 690 million light years from Earth. Previously, scientists discovered an enormous filament, a thin strip of very hot gas, that stretched for at least 50 million light years. This new study found evidence that the Northern Clump is traveling along this filament, similar to how a car moves along the interstate.

A variety of telescopic images allowed the researchers to observe the galaxy cluster and its movement. Yuanyuan Su, an assistant professor in the University of Kentucky Department of Physics and Astronomy, is one of the lead researchers on the project and led the analysis of the X-ray observation taken by the Chandra X-ray Observatory.

The Chandra telescope has an unprecedented spatial resolution among X-ray telescopes, which reveals a sharp contact edge towards south as the cluster travels through the cosmic filaments.

"In theory and simulations, massive objects in the universe are predicted to grow through the accretion of substructures along the filament of dark matter. It is exciting that such an event is caught in action thanks to the joint observations of X-ray, optical and radio telescopes," Su said. "More discoveries like this are expected over the next few years, particularly with eROSITA, a newly launched survey observatory aiming to provide the deepest view of the X-ray sky."

Previous observations from eROSITA have shown that the Northern Clump and a pair of galaxy clusters to the south all lie along an enormous filament of gas. The Northern Clump is moving toward the other clusters and all three will eventually merge with each other.

Led by Angie Veronica of the University of Bonn in Germany, the results were presented at the recent European Astronomical Society meeting. UK's Su served as second author on the paper, which is available online.

Read more about the project at https://chandra.si.edu/photo/2021/nclump/.

The University of Kentucky is increasingly the first choice for students, faculty and staff to pursue their passions and their professional goals. In the last two years, Forbes has named UK among the best employers for diversity, and INSIGHT into Diversity recognized us as a Diversity Champion four years running. UK is ranked among the top 30 campuses in the nation for LGBTQ* inclusion and safety. UK has been judged a “Great College to Work for" three years in a row, and UK is among only 22 universities in the country on Forbes' list of "America's Best Employers."  We are ranked among the top 10 percent of public institutions for research expenditures — a tangible symbol of our breadth and depth as a university focused on discovery that changes lives and communities. And our patients know and appreciate the fact that UK HealthCare has been named the state’s top hospital for five straight years. Accolades and honors are great. But they are more important for what they represent: the idea that creating a community of belonging and commitment to excellence is how we honor our mission to be not simply the University of Kentucky, but the University for Kentucky.