Webb measures extreme gas outflows from distant 'dead' galaxies

Astronomers using the James Webb Space Telescope have measured the most powerful gas outflow ever recorded from a "dead" galaxy outside our cosmic neighborhood. The study focused on 23 massive, quiescent galaxies from roughly 11–13 billion years ago, detecting neutral gas outflows using the sodium "Na I D" absorption doublet. The outflows in these galaxies were found to be 10–100 times more massive than those measured in previously studied galaxies. The research highlights that even outflows of this magnitude may not be sufficient to permanently stop star formation. Among the 23 galaxies, 13 showed excess Na I D absorption, with seven displaying clear blueshifted absorption, indicating gas moving toward us. The gas is more likely to fall back into the galaxy rather than escape, suggesting a short-lived fountain cycle rather than a permanent quenching event.

The study found that the outflow rates in these galaxies exceeded the ongoing star-formation rate, but the gas was not fast enough to escape the galaxy permanently. The outflows are linked to active black holes, but the exact mechanism driving them is not yet established. One galaxy, DD-236, showed the most extreme outflow rate, accompanied by signs of an actively feeding black hole. The research indicates that the link between black hole activity and outflows is not well understood, with only two of the 13 galaxies with outflows showing signs of actively feeding black holes. The two most extreme outflows are linked to active black holes, but their origins are not directly tied to ongoing AGN activity or recent starbursts.

The study emphasizes that the outflows are likely short-lived and not directly responsible for quenching star formation. The results provide insight into how galaxies evolve and die, particularly through the role of gas outflows and black hole activity. The findings are part of a broader effort to understand the formation and evolution of galaxies in the early universe.

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