The stellar wind controls the growth of galaxies

Madrid, 7 Dec. (Europe Press) –

For the first time in three dimensions, astronomers have observed gas in spiral galaxies being pumped up and down at high speeds. Far from the galaxy.

The observations confirm the current theory of galactic evolution, which states that star-forming galaxies drive the intergalactic wind by ejecting gas across the poles. The astronomers published their findings in Nature.

Gas flows are important in models describing galaxy formation. Galaxies grow by the influx of gas from their surroundings. That growth is thought to be inhibited by supermassive black holes that eject gas into space through young stars and shock waves. Exactly what happens is not known, but without a strong gas flow, galaxies become very massive.

Researchers have now made the first convincing case that galaxies reach beyond galaxies. They used the MUSE instrument at the Largest Telescope in Chile. They analyzed the signal of magnesium gas around nearly two hundred distant spiral galaxies. In half of these galaxies they observed the edge-on disk. The other half saw the disc from the front as a circle.

In the edge group of galaxies, the gas outflow was vertical up and down. “We detected gas tens of light-years from the galaxy, moving through intergalactic space at hundreds of kilometers per second,” he says. It is a statement First author Yucheng Guo of the University of Lyon.

“For me this is a real milestone, that we are finally seeing intergalactic gas leakage from normal galaxies,” says Jupp Schae from Leiden University. He is a co-author of the study and has been researching interstellar winds and gas flows for several years. “Until now the observations have been difficult to interpret. But thanks to this study we can no longer ignore the bipolar wind.”

Now that astronomers have mapped the average gas flow and velocities, they can test and fine-tune computer simulations of galaxy evolution. This is important because it will clarify how galaxies grow.