One way for massive stars, at least 10 times the size of the Sun, to meet their end is by exploding into a supernova. In other words, it is a massive explosion caused by the star’s core running out of fuel.
One of the consequences of a supernova explosion is the generation of galactic winds, which play an important role in controlling star formation. Galactic winds have already been observed in some nearby galaxies, but now a team of scientists has for the first time directly observed the phenomenon in a large population of galaxies in the distant Universe, when galaxies are in their early stages of formation. did.
by research According to lead author Yucheng Guo of the Lyon Center for Astrophysics, galactic winds are an important part of galactic evolution models.
“It was thought that there was a galactic wind that could control the growth of galaxies. However, it was extremely difficult to directly observe this wind. Our research shows that in the early stages of the universe, all normal “This shows that there are such winds in the galaxy,” Guo said.
According to Guo, galactic winds form an important part of so-called feedback processes that are important for understanding the evolution of galaxies. “Galactic winds occur as a result of star-forming activity. These winds inject a lot of energy and momentum into the gas, resulting in [being] Banished from the galaxy. If there is not enough gas in a galaxy, star formation stops. This is called the feedback process,” he said.
According to Guo, galactic winds also enable the exchange of material between galaxies and their surroundings. “Each galaxy is surrounded by a halo of gas. Galaxies can not only breathe in gas, but also breathe it out,” Guo said.
hard to see
He said it has traditionally been very difficult to observe galactic winds because gas halos are nearly transparent.
Guo and his team overcame this hurdle by using the Very Large Telescope’s Multi-Unit Spectroscopic Explorer (MUSE) instrument. “This instrument can observe galaxies at redshift z≈1, which corresponds to 7 billion years of the evolution of the universe,” Guo said. He said that radiation from magnesium atoms can be detected and directly observed.
He said another important feature of this study was the successful observation of galactic winds in more than 100 galaxies. “We were also able to detect the average shape of the wind, like an ice cream cone,” he said.
Guo said direct observation of galactic winds outside the local universe is the first step in the research. “We still don’t know its physical properties, such as its size and power, and how they change over time and across different types of galaxies.”
Nature, 2023. DOI: 10.1038/s41586-023-06718-w
Dhananjay Kadirkar is a Paris-based journalist.