Astrononomers using the NASA/ESA/CSA James Webb Space Telescope have detected that GS-10578, a massive, quiescent galaxy at redshift of 3.064 (look-back time 11.7 billion years), is expelling large amounts of gas at speeds of about 1,000 km per second, which is fast enough to escape the galaxy’s gravitational pull; these fast-moving winds are being ‘pushed’ out of the galaxy by the central supermassive black hole.
GS-10578 represents a unique opportunity to study how the most massive galaxies in the Universe became — and stayed — quiescent. Image credit: Francesco D’Eugenio.
“The Universe today is not what it used to be,” said University of Cambridge’s Kavli Institute for Cosmology astronomer Francesco D’Eugenio and his colleagues.
“Local, massive, quiescent galaxies stand like colossal wrecks of glorious but remote star-formation histories and mighty and rapid quenching, the likes of which have no present-day equals.”
“Webb has enabled us for the first time to witness these monumental galaxies during the long-gone epoch when they arose and fell.”
“By redshift of 1.5-2 (3-4 billion years after the Big Bang), massive quiescent galaxies have little to no cold gas, the fuel for star formation.”
“However, the question whether the missing fuel was consumed by starbursts or whether it was removed by ‘ejective’ feedback from supermassive black holes remains open.”
To address this question, the astronomers observed GS-10578, a galaxy roughly the size of the Milky Way in the early Universe, about two billion years after the Big Bang.
“Based on earlier observations, we knew this galaxy was in a quenched state: it’s not forming many stars given its size, and we expect there is a link between the black hole and the end of star formation,” Dr. D’Eugenio said.
“However, until Webb, we haven’t been able to study this galaxy in enough detail to confirm that link, and we haven’t known whether this quenched state is temporary or permanent.”
GS-10578 is massive for such an early period in the Universe: its total mass is about 200 billion times the mass of our Sun, and most of its stars formed between 12.5 and 11.5 billion years ago.
Using Webb, the researchers detected that the galaxy is expelling large amounts of gas at speeds of about 1,000 km per second, which is fast enough to escape the galaxy’s gravitational pull.
These fast-moving winds are being ‘pushed’ out of the galaxy by the central supermassive black hole.
Like other galaxies with accreting black holes, GS-10578 has fast outflowing winds of hot gas, but these gas clouds are tenuous and have little mass.
Webb detected the presence of a new wind component, which could not be seen with earlier telescopes.
This gas is colder, which means it’s denser and — crucially — does not emit any light.
Webb, with its superior sensitivity, can see these dark gas clouds because they block some of the light from the galaxy behind them.
The mass of gas being ejected from the galaxy is greater than what the galaxy would require to keep forming new stars.
“We found the culprit. The black hole is killing this galaxy and keeping it dormant, by cutting off the source of ‘food’ the galaxy needs to form new stars,” Dr. D’Eugenio said.
“Although earlier theoretical models had predicted that black holes had this effect on galaxies, before Webb, it had not been possible to detect this effect directly.”
“We knew that black holes have a massive impact on galaxies, and perhaps it’s common that they stop star formation, but until Webb, we weren’t able to directly confirm this,” said Professor Roberto Maiolino, also from the Kavli Institute for Cosmology at the University of Cambridge.
“It’s yet another way that Webb is such a giant leap forward in terms of our ability to study the early Universe and how it evolved.”
The team’s results were published in the journal Nature Astronomy.
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F. D’Eugenio et al. A fast-rotator post-starburst galaxy quenched by supermassive black-hole feedback at z = 3. Nat Astron, published September 16, 2024; doi: 10.1038/s41550-024-02345-1
