NASA | Goddard | 2016 July 06
Measurements of unprecedented detail returned by Japan's Hitomi satellite have allowed scientists to track the motion of X-ray-emitting gas at the heart of the Perseus cluster of galaxies for the first time. The results showcase the long-awaited premiere of a next-generation X-ray instrument whose key components were developed at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
Led by the Japan Aerospace Exploration Agency (JAXA), Hitomi was launched on Feb. 17. Following the successful activation of the observatory and instruments, Hitomi suffered a mission-ending spacecraft anomaly on March 26.Click to play embedded YouTube video.
Before its demise, though, Hitomi was able to peer into the Perseus cluster of galaxies, an assemblage of thousands of galaxies bound together by gravity. Located about 240 million light-years away and named for its host constellation, the Perseus galaxy cluster contains a vast amount of extremely hot gas. At temperatures averaging 90 million degrees Fahrenheit (50 million degrees Celsius), the gas glows brightly in X-rays. Prior to Hitomi's launch, astronomers lacked the capability to measure the detailed dynamics of this gas, particularly its relationship to bubbles of gas expelled by an active supermassive black hole in the cluster's core galaxy, NGC 1275. ...
Hitomi's revolutionary Soft X-ray Spectrometer (SXS), developed and built by Goddard scientists working closely with colleagues from several institutions in the United States, Japan, and the Netherlands, spent more than two and a half days observing a wide area in the cluster's core. The resulting X-ray spectrum, which provides 30 times the detail of the best previous observation, unveiled a rich landscape of X-ray emission lines from iron, nickel, chromium, and manganese -- metals forged in billions of massive stars in the cluster's galaxies and dispersed when they exploded as supernovae.
The SXS studied a square patch of the sky measuring about 195,000 light-years on a side at the cluster's distance. The total range of gas velocities directed toward or away from Earth within this square was found to be about 365,000 miles an hour (590,000 kilometers per hour) -- enormous by human standards but surprisingly modest on cosmic scales. The observed velocity range indicates that turbulence is responsible for only about 4 percent of the total gas pressure. This result is of particular interest to astrophysicists. Turbulent pressure was a previously unmeasured quantity that could significantly impact estimates of the cluster's mass. The SXS measurements show that only minor corrections are needed. ...
Hitomi Measures X-ray Winds of the Perseus Galaxy Cluster
NASA | Goddard Media Studios | 2016 July 06
Hitomi Finds Quiet Space in the Heart of the Perseus Galaxy Cluster
Yale University | 2016 July 06
How Stars Are Born and Cosmic Structures Evolve
Standford University | 2016 July 06
Galaxy Cluster Keeps Calm and Carries on Radiating X-rays
ESA | Science & Technology | Hitomi | 2016 July 06
Dead X-ray Satellite Reveals Galaxy Cluster Surprise
Nature News | 2016 July 06
The Quiescent Intracluster Medium in the Core of the Perseus Cluster - Hitomi Collaboration
- Nature 535(7610):117 (07 July 2016) DOI: 10.1038/nature18627
arXiv.org > astro-ph > arXiv:1607.04487 > 15 Jul 2016
