Stellar winds regulate growth of galaxies

Galactic winds enable the exchange of matter between galaxies and their surroundings. In this way, they limit the growth of galaxies, that is, their star formation rate. Although this had already been observed in the local universe, an international research team led by a CNRS scientist1  has just revealed—using MUSE,2  an instrument integrated into the European Southern Observatory’s (ESO) Very Large Telescope—the existence of the phenomenon in galaxies which are more than 7 billion years old and actively forming stars, the category to which most galaxies belong. The team’s findings, to be published in Nature on 6 December 2023, thus show this is a universal process.

Galactic winds are created by the explosion of massive stars. As they are diffuse and of low density, they are usually hard to spot. To see them, the scientists combined images of more than a hundred galaxies obtained through very long exposure times. By studying magnesium atom emission signals, the team was also able to map the morphology of these winds, which appear as cones of matter perpendicularly ejected from both sides of the galactic plane.

In the future, the researchers hope to measure how far these winds extend and the quantity of matter they transport.

• 1The team’s leader is affiliated with the Centre de Recherche Astrophysique de Lyon (CNRS / ENS de Lyon / Claude Bernard Lyon 1 University). Scientists from the Galaxies, Étoiles, Physique, Instrumentation (GEPI) (CNRS / Paris Observatory–PSL) research laboratory and multiple international research teams also participated.
• 2The Multi-Unit Spectroscopic Explorer (MUSE) is operated by seven leading European research laboratories, including the Centre de Recherche Astrophysique de Lyon, which oversees MUSE activities.