Post-starburst galaxies don’t scatter all of their star-forming fuel, reveals new study

New data from the Atacama Large Millimeter/submillimeter Array (ALMA) has revealed that post-starburst galaxies (PSBs) don't scatter all of their star-forming fuel. They actually hold onto and condense star-forming fuel near their centers, and then don't use it to form stars.

The new results challenge the previous theory that post-starburst galaxies scatter all of their gas and dust - the fuel required for creating new stars - in violent bursts of energy, and with extraordinary speed, leading to quiescence, a time when galaxies stop forming stars.

What keeps them from forming stars?

"We've known for some time that large amounts of molecular gas remains in the vicinity of PSBs but haven't been able to say where, which in turn, has prevented us from understanding why these galaxies stopped forming stars. Now, we have discovered a considerable amount of remaining gas within the galaxies and that remaining gas is very compact," said Adam Smercina, an astronomer at the University of Washington and the principal investigator of the study.

According to the researchers, in addition to being compact enough to make stars, the gas in the observed dormant - or quiescent - galaxies was often centrally-located, though not always, and was surprisingly turbulent.

"These results raise the question of what energy sources are present in these galaxies to drive turbulence and prevent the gas from forming new stars. One possibility is energy from the accretion disk of the central supermassive black holes in these galaxies," explained Decker French, an astronomer at the University of Illinois, and a co-author of the research.

This discovery gives researchers one more clue to solving the mystery of how galaxies in particular live, evolve and die over the course of billions of years, the National Radio Astronomy Observatory said in a media release on Monday.

The study findings are published today in The Astrophysical Journal.