The universe's 'most relaxed' galaxy cluster was shaped by cosmic violence, new study finds

For decades, astronomers have described the galaxy cluster Abell 2029, a vast city of galaxies in the Virgo constellation, as "the most relaxed clusters in the universe." But beneath that placid exterior, scientists have now found, the cluster is still reverberating from an ancient cosmic collision. New observations from the Chandra X-ray Observatory suggest giant "sloshing" motions in the cluster's gas — triggered by a merger roughly 4 billion years ago — may help heat the cluster alongside energy released by the supermassive black hole at its center. That could help explain why the gas in galaxy clusters does not cool as quickly as expected, the researchers say. But of note, Chandra's new data also revealed massive substructures still visible today, including gigantic spirals, shock fronts and waves of superheated gas rippling through the cluster, according to a statement released last week by Chandra X-ray Observatory. "Overall, our results suggest that A2029 is still settling from past interactions," a team of researchers led by astrophysicist Courtney Watson of Boston University write in the new paper, "showing that even the initially most relaxed-looking clusters can be hiding a rich history of dynamical activity." Hosting more than a thousand galaxies, Abell 2029 is among the largest known galaxy clusters, which are sprawling collections of galaxies bound together by gravity and immersed in enormous clouds of heated gas. …