Astronomers examining the nearby universe with the help of the Atacama Large Millimeter/submillimeter Array (ALMA) have just completed the largest high-resolution survey of star-forming fuel ever conducted in galaxy clusters, writes Amy Oliver of the National Radio Astronomy Observatory. More important, they are tackling a long-standing mystery in astrophysics: What is killing galaxies? The research, which provides the clearest evidence to date that extreme environments in space have severe impacts on the galaxies within them, will be published in an upcoming edition of The Astrophysical Journal Supplement Series. The Virgo Environment Traced in Carbon Monoxide Survey – VERTICO – set out to better understand star formation and the role of galaxies in the universe. “We know that galaxies are being killed by their environments, and we want to know why,” said Toby Brown, Plaskett Fellow at the National Research Council of Canada and lead author on the paper. “What VERTICO reveals better than ever before is which physical processes affect molecular gas and how they dictate the life and death of the galaxy.” Home to thousands of galaxies, the Virgo Cluster is the nearest massive cluster of galaxies to the Local Group, where the Milky Way resides. The extreme size and proximity make the cluster easy to study, but it has other features that make it ripe for observation. “The Virgo Cluster is a bit unusual in that it has a relatively large population of galaxies that are still forming stars,” said Christine Wilson, professor at McMaster University and co-principal investigator on the VERTICO project. “Many galaxy clusters in the universe are dominated by red galaxies with little gas and star formation. The VERTICO project observed the gas reservoirs of 51 galaxies in the Virgo Cluster in high-resolution, revealing an environment so extreme that it can stop entire galaxies from forming stars in a process known as galaxy quenching. “The Virgo Cluster is the most extreme region of the local universe, filled with million-degree plasma, extreme galaxy speeds, violent interactions between galaxies and their surroundings, a galaxy retirement village, and accordingly, a galaxy graveyard,” said Brown, adding that the project revealed how gas stripping can stunt, or shut down, one of the most important physical processes in the universe: star formation. “Gas stripping occurs when galaxies are moving so fast through hot plasma in the cluster that vast quantities of cold molecular gas are stripped away from the galaxy, as though the gas is being swept away by a huge cosmic broom, said Brown. “The exquisite quality of VERTICO’s observations allows us to better see and understand such mechanisms.”
https://phys.org/news/2021-11-cosmic-whodunit-alma-galaxies-star-forming.html
