Chandra and ALMA measure speed of sloshing gas in galaxy cluster
(PHYSorg.com Space & Earth)

Almost all galaxy clusters experience mergers. While a merger takes place, a specific spiral pattern can often be observed in X-ray images. Such a spiral feature is due to the motion of the sloshing gas induced by a merger. Observing a phenomenon similar to sloshing gas in the daily life is easy: When you swirl a wine glass containing liquid, you will see how the water rotates along with the glass. Discovering how fast the sloshing gas moves in galaxy clusters has profound astronomical meaning and therefore is of great interest to astronomers. A group of researchers from Taiwan and Japan has now measured it using a novel technique.