Galaxy Cluster Relaxed Now, but was Wild in the Past

Galaxy Cluster Relaxed Now, but was Wild in the Past Abell 2029 More images and information Credit: X-ray: NASA/CXC/CfA/C. Watson et al.; Optical: PanSTARRS; Image Processing: NASA/CXC/SAO/N. Wolk and P. Edmonds The galaxy cluster Abell 2029 is sometimes described as “the most relaxed cluster in the Universe.” This moniker does not arise from some sort of mellow vibe, but rather because of how calm and undisturbed the superheated gas that pervades the cluster appears to be. New observations from NASA’s Chandra X-ray Observatory clearly show that Abell 2029 had a much more colorful history than its current disposition suggests. The latest study finds that Abell 2029 is still settling down after a raucous collision with another smaller cluster about four billion years ago. Galaxy clusters are the largest structures in the Universe held together by gravity. They are made up of hundreds or even thousands of galaxies, unseen dark matter, and a huge amount of gas that fills in the space between the galaxies. This gas is typically heated to millions of degrees, which makes it glow in X-ray light. A team led by astronomers from Boston University (BU) and the Center for Astrophysics