The Surprising Dispersion of the Galactic Wind

The MUSE instrument has revealed that „galactic winds” — the ejection of massive material from galaxies — are a frequent phenomenon. The discovery, by observing about 100 galaxies, provides significant insights into the role of these outflows in galaxy evolution and confirms theoretical models. Credit: SciTechDaily.com

Recent research using Muse The instrument shows that interstellar winds, essential for galaxy evolution, are a common phenomenon in the Universe, challenging previous assumptions about their rarity.

Under certain circumstances galaxies release large amounts of material into their environment, fueled by a large number of massive starbursts. In muse tool A very large telescope of the European Southern Observatory (That) has now demonstrated for the first time that such „galactic winds” are not rare, but actually frequent.

Discovery of Double Cone Systems

When an international research team led by the Center National de la Recherche Scientifique (CNRS) examined a sample of about 100 galaxies, they found characteristic double-cone structures in the galactic wind. However, these are visible only in certain spectral lines of light and only if the sensitivity of the measurement is very high. Previously only a few such cases were known, most of which were discovered by the MUSE instrument.

Theoretical sketch for the interstellar wind. The background distribution (red) shows the gas emission of galaxies detected by MUSE. Credit: Guo et al. 2023, AIP.

Professor Lutz Vysotsky, Head of the Galaxies and Quasars Division at the Leibniz Institute for Astrophysics Potsdam (AIP) and co-author of the article in Science Nature states: “MUSE shows us that such galaxy-scale outflows exist in nearly every star-forming galaxy. Additionally, the new results allow us to identify exactly what size and shape these interstellar winds typically have. Until now, this has only been possible in very rare extreme cases.

The role of outgassing in cosmic evolution

The outflowing gas is thought to play an important role in the cosmic evolution of galaxies by regulating their growth and star formation. Theoretical calculations predict outward „dipole” shapes that extend above and below the galactic plane into the circumstellar medium. Similar patterns can be directly observed in some nearby galaxies, such as the „cigar galaxy” M82, and even in our own. milky wayBut there we can see only the inner parts and cannot form the overall picture.

A galactic wind is found in nearby galaxies such as M82, which is known as the „Cigar Galaxy” because of its shape. Credit: NASA, ESA, Hubble; Processing & Copyright: Harshvardhan Pathak

Galactic Wind in the Young Universe

Cosmological simulations of galaxy formation predict that the event of interstellar winds for the young universe occurred more frequently and strongly in these early stages: due to the high star formation activity of young galaxies, there were more supernova explosions and stronger outflows. These transport gas and energy from a galaxy to its surroundings, thus depriving it of the fuel needed for further star formation, while enriching its „circular” environment. This so-called feedback process may be an important component in our understanding of the formation and evolution of galaxies, but it is not sufficiently constrained by observations due to the difficulty of detecting the phenomenon.

New insights from MUSE

A new study with the MUSE instrument has now directly shown that the galaxy's surroundings reach more than 30,000 light-years away. The visible signal depends on the orientation of the galaxy relative to the line of sight: if the system is viewed from the side, there is strong emission above and below the plane of the galaxy, whereas for galaxies „above” or „below,” the signal is weak and unevenly distributed. These observations were theoretically predicted in advance by the dipole pattern of emission perpendicular to the plane of the galaxy.

Reference: Yucheng Guo, Roland Bacon, Nicholas F. Bouche, Lutz Vysotsky, Jupp Shaye, Jeremy Plaisot, Ann Wareham, Sebastiano Cantal, “Bipolar outflows for massive galaxies at redshift z ≈ 1 at 10 kpc. 2010; Jarle Brinchmann, Maxime Cherrey, Haruka Kusakabe, Ivanna Langan, Floriane Leclercq, Jorryt Matthee, Leo Michel-Dansac, Ilane Schroetter and Martin Wendt, 6 December 2023, Nature.
DOI: 10.1038/s41586-023-06718-w