Arizona State University astronomers announced on Mar. 25 that they have helped an international team directly measure the speed of a superheated wind at the center of the nearby galaxy M82 for the first time.
The finding is important because it gives scientists new insight into how galaxies grow and change over time. Understanding these galactic winds helps researchers learn more about how stars form and how galaxies evolve.
Professor Evan Scannapieco and PhD candidate Skylar Grayson from ASU’s School of Earth and Space Exploration contributed to measuring gas in M82 moving at speeds exceeding 2 million miles per hour, fast enough to travel from Earth to the moon in about six minutes. The results were published in Nature, using data from the Resolve instrument aboard the XRISM spacecraft, which can detect subtle changes in X-ray light coming from extremely hot gas.
Grayson said, “Some of our early models of starburst galaxies were developed in the 1980s, and we’re finally able to test them in ways that weren’t possible before XRISM. It’s fun because it provides opportunities to figure out why the model might not be capturing everything that’s going on in the real universe.” The team found that thanks to XRISM’s high resolution and sensitivity, they could measure both speed and temperature by analyzing X-ray signals from ultrahot iron near M82’s core. This revealed a gas temperature around 45 million degrees Fahrenheit—about 5,000 times hotter than our sun’s surface—and confirmed that this heat alone can drive large-scale outflows without extra pressure from cosmic rays.
Scannapieco said, “Outflows like this are one of the most important ways that galaxies regulate their growth. By finally measuring the speed of the hot gas in M82, we are one step closer to building realistic models of how star-driven feedback drives galaxy evolution over cosmic time.” Still, questions remain: each year enough gas leaves M82’s center for seven solar-mass stars but only four solar masses go into these winds; researchers hope future studies will reveal where the rest goes.
Arizona State University has been recognized for its innovative work across many fields; the university was named number one for innovation by U.S. News & World Report for eight consecutive years according to nominations by college leaders nationwide.
In addition to astronomy research, ASU collaborates with local partners on technology projects such as a pilot program with Argos Vision developing smart traffic cameras aimed at improving safety through advanced data analysis according to a press release by Phoenix Street Transportation Department.
