The Perseus galaxy cluster is filled with hot X-ray-emitting gas, as seen in this image from NASA’s Chandra X-ray Observatory. Astronomers using the Soft X-ray Spectrometer aboard the Hitomi satellite have, for the first time, mapped the motion of this gas and determined its velocity structure across a large part of the cluster. The square overlay, which spans about 195,000 light-years at the cluster’s distance, shows the area observed by Hitomi. Colors correspond to the detected gas speeds, with bluer colors indicating faster motion toward Earth and redder colors showing greater velocities in the opposite direction. Credit: NASA Goddard and NASA/CXC/SAO/E. Bulbul, et al.
A doomed Japanese satellite managed to capture a view of a galaxy cluster 250 million light years away just before it died, scientists have revealed.
Launched on February 17, the Hitomi X-ray satellite began tumbling out of controlin March when contact was finally lost.Just before its demise, scientists managed to extract data measuring X-ray activity in the Perseus galaxy cluster.Published in Nature, data revealed the movement of gas between galaxy clusters was not as turbulent as expected.
The Japan Aerospace Exploration Agency (JAXA) mission was initially intended to study galaxy formation and how black holes interact with spacetime. Hitomi carried an instrument named the Soft X-ray Spectrometer (SXS) that allowed scientists to measure the movement of gas in the Perseus galaxy cluster, just before the mission was lost.
Hitomi measured the motion of gas in the center of the Hitomi measured the motion of gas in the center of the the Perseus galaxy cluster with unprecedented precision, as much as 50 times better than previous instruments, said Andrew Fabian, a professor of astronomy at the University of Cambridge in England. The black hole, by stirring the gas, keeps the material from cooling down and forming new stars.
“Being able to measure gas motions is a major advance in understanding the dynamic behavior of galaxy clusters and its ties to cosmic evolution,” study co-author Irina Zhuravleva said in a statement by the SLAC National Accelerator Laboratory in Menlo Park, Calif. “Although the Hitomi mission ended tragically after a very short period of time, it’s fair to say that it has opened a new chapter in X-ray astronomy.” The Perseus galaxy cluster, the last thing Hitomi saw before it broke apart, is located 240 million light-years away, and is filled with gas that can reach temperatures of about 90 million degrees Fahrenheit. The cluster also contains a supermassive black hole, with the region around it expelling massive amounts of gas, the movement of which scientists sought to measure.
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Hitomi was the third attempt to fly a “microcalorimeter” in space—an instrument that is cooled almost to absolute zero and can read the precise energy of each incoming x-ray photon it receives. This provides high-resolution measurements of the various wavelengths of light coming from the wide field of view it observes.
Astronomers say that despite Hitomi’s early demise, its discoveries mark a “new chapter in X-ray astronomy.” Two previous attempts at using microcalorimetry technology failed in the early 2000s. The next similar mission is scheduled to be launched in 2028.
- The quiescent intracluster medium in the core of the Perseus cluster. Nature 535, 117–121 (07 July 2016) doi:10.1038/nature18627