Latest Spectroscopic Observations Uncover Remarkable Gas Ejection and its Potential Impact on Galactic Evolution
The James Webb Space Telescope has truly changed the way we look into the cosmos. In addition to the countless mouthwatering images of the universe it produced, it has not fallen short in the amount of science it has provided us with. When astronomers turned the James Webb Space Telescope (JWST) toward the galaxy named COSMOS-11142, they weren’t expecting such a significant discovery. The deep spectroscopic observations brought to light a massive and multiphase outflow of both neutral and ionized gas in this galaxy, a discovery that was recently unveiled in a paper on the arXiv pre-print server.
Delving into COSMOS-11142’s Traits
Located at a redshift of 2.445, COSMOS-11142 is a vast galaxy, spanning a half-light radius of around 2,000 light years. Previous research labeled it as a “post-starburst” galaxy, characterized by a star-formation phase that has recently been rapidly quenched. This quenching has rendered its current star-formation rate to an estimated one to 10 solar masses annually.
The lead of the observational team, Sirio Belli from the University of Bologna in Italy, stated, “We targeted COSMOS-11142 as part of the Blue Jay survey, a Cycle-1 JWST program that encompassed about 150 galaxies uniformly spread in redshift z (1.7 < z < 3.5) and stellar mass M∗ (log M∗/M⊙ > 9).”
Results from JWST portrayed COSMOS-11142 as a compact, elongated, and somewhat dusty galaxy. Boasting a dynamical mass close to 70 billion solar masses, its metallicity is approximated to be at 0.16.
The Stellar Revelation: A Massive Gas Outflow
The heart of the discovery was the evidence of a gas outflow, both neutral and ionized, during the rapid halting of star formation in COSMOS-11142. This outflow showed remarkable mass outflow rates: 100 solar masses per year for neutral gas and one solar mass per year for ionized gas. Intriguingly, these rates are substantially larger than what is commonly observed in local star-forming galaxies.
Furthermore, the outflow rate in COSMOS-11142 surprisingly surpasses its residual star-formation rate. This points to the significant influence the gas ejection has on the galaxy’s evolution, with researchers theorizing that this outflow is propelled by active galactic nucleus (AGN) feedback.
Conclusions and Implications
Considering the findings, the team surmises that the observed outflow is pivotal in the rapid quenching observed in COSMOS-11142. They further propose that halo gas heating via radio-mode AGN feedback might be crucial to keep this galaxy in a quiescent state.
As the researchers emphasize, “The system is confirmed as a post-starburst galaxy. It amassed most of its stellar mass through a rapid starburst roughly 300 million years prior to our observations, only to see its star formation rate plummet drastically.”
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