A team of astronomers from the University of California at San Diego, along with a group of international researchers, joined forces to study cosmic winds within galaxies. They spotted a galactic wind mass exiting a distant galaxy known as Makani. The study published in the journal Nature offered the first evidence that the galactic wind has an essential role in the formation of the so-called circumgalactic medium (CGM).
“Makani is not a typical galaxy. It’s what’s known as a late-stage major merger—two recently combined similarly massive galaxies, which came together because of the gravitational pull each felt from the other as they drew nearer,” explained Alison Coil from the University of California at San Diego.
Coil highlighted that the majority of cosmic gas gathers around the galaxies and not inside them. That phenomenon is yet to be explained by astronomers.
Galactic Wind Exiting Distant Galaxy Spotted By Astronomers
“Galaxy mergers often lead to starburst events, when a substantial amount of gas present in the merging galaxies is compressed, resulting in a burst of new star births. Those new stars, in the case of Makani, likely caused the huge outflows—either in stellar winds or at the end of their lives when they exploded as supernovae. While these events may occur at some point in a galaxy’s life, they’d be relatively brief,” added Alison Coil.
For this study, astronomers employed the W. M. Keck Observatory’s new Keck Cosmic Web Imager (KCWI) instrument and combined the observations with images taken by NASA’s Hubble Space Telescope.
The images collected from the two instruments helped scientists study ionized oxygen gas and the structure of the Makani galaxy. Also, they noticed that the galactic wind is exiting the galaxy. “This means that we can confirm it’s actually moving gas from the galaxy into the circumgalactic regions around it, as well as sweeping up more gas from its surroundings as it moves out,” said David Rupke from Rhodes College.