Titanic merger of galaxy clusters revealed

One of the hottest, most energetic mergers of two colossal galaxy clusters has been imaged in exquisite detail by an X-ray observatory in space, astronomers announced on Thursday. The collision is one of the most powerful cosmic events ever witnessed by astronomers.

The observation showcases how all structures in the universe are thought to grow and bolsters recent observations that the largest structures in the universe are still evolving.

An international team of astronomers led by Patrick Henry of the University of Hawaii used Europe’s XMM-Newton observatory to study a massive galaxy cluster called Abell 754. The cluster is relatively close to Earth at 800 million light-years away and, unlike other energetic mergers, does not lie in the plane of the Milky Way, making it easier to observe.

The cluster spans 3 million light-years across and, if it were visible in the sky, it would cover half of the Moon. It appears to be made up of two smaller galaxy clusters, one crammed with 1000 galaxies and the other with 300. Shock waves caused by the merger, which may have begun 300 million years ago. has heated gas in the clusters to extreme temperatures – about 100 million degrees C.