By Ron Cowen
Astronomers last week unveiled the most detailed image ever taken of a rare type of cosmic train wreck—the collision of two of the universe’s most massive clusters of galaxies. Taking place over several hundred million years, the merger is the most powerful that’s ever been so clearly recorded, says Patrick Henry of the University of Honolulu in Hawaii. He and his collaborators described the findings during a NASA telephone briefing on Sept. 23 and will report additional details in an upcoming Astrophysical Journal.
Henry and his colleagues used the European Space Agency’s XMM-Newton Telescope to document the X-ray emissions from hot gas in the cluster Abell 754. Containing about 1,000 galaxies, Abell 754 is one of the massive clusters nearest to Earth, residing 800 million light-years away. Astronomers estimate that only a few hundred massive clusters exist simultaneously in the cosmos and that only 20 to 30 of them are in the midst of collisions.