HITOMI’s last “words”


HITOMI, the most sensitive X-ray satellite, was destroyed in March 2016, about a month after its launch. Despite its early destruction, HITOMI managed to perform significant science. The spacecraft observed the Perseus cluster, the brightest X-ray cluster in the sky, for three days. Analyzing the data, astronomers measured the motion of gas in the centre of the cluster with unprecedented precision, more than 50 times better than previous instruments.

Hot gas makes up about 15 percent of a cluster. Supermassive black holes stir this gas, preventing it from cooling down and thus keeping star formation at a minimum. Without that mixing activity from the black hole, galaxies would be much brighter and have a much higher stellar mass. HITOMI observations showed that in the Perseus cluster, gas moves with a speed of about only 160 kilometers per second, surprisingly slow considering how disturbed the region looks in X-ray images.

As Dr. Zhuravleva, a co-author of the relevant study, stated: “Being able to measure gas motions is a major advance in understanding the dynamic behavior of galaxy clusters and its ties to cosmic evolution… Although the HITOMI mission ended after a very short period of time, it’s fair to say that it has opened a new chapter in X-ray astronomy”.


Publication: Aharonian et al. 2016

Source: Space.com