Gas location not volume key to star formation in galaxies

The study, led by PhD candidate Seona Lee from The University of Western Australia's ICRAR node, utilized data from around 1,000 galaxies mapped by CSIRO's ASKAP radio telescope, part of the WALLABY survey. This effort marks a major advancement over prior surveys that assessed gas distribution in only a few hundred galaxies.

The findings reveal that galaxies forming stars typically exhibit denser accumulations of atomic hydrogen gas in their stellar regions, rather than simply possessing large total gas reserves.

"It was very exciting to see a correlation between star formation and where the atomic hydrogen gas is located," said Lee.

ASKAP's high-resolution capabilities enabled the team to precisely determine both the location and density of this atomic gas across an unprecedented number of galaxies.

Professor Barbara Catinella, ICRAR Senior Principal Research Fellow and co-leader of the WALLABY survey, emphasized the significance of gas distribution using a culinary analogy. "While different cakes require different amounts of flour, to bake a cake properly, you focus on the flour that's in the bowl, not the unused flour left in the package," she said.

Understanding where the gas is dense enough to support star formation, rather than assessing the total galactic gas, is central to determining how stars are born and how galaxies evolve. The team examined both radio wave and optical data to evaluate gas levels in star-forming regions.

"To learn about how stars are formed, we had to measure the atomic hydrogen gas in areas where stars are actively coming to life," Lee added. "This is important for figuring out just how much gas is really supporting the creation of new stars."

Research Report:WALLABY - The ASKAP HI All-Sky Survey