The James Webb Space Telescope (JWST) and the Atacama Large Millimeter/submillimeter Array (ALMA) have jointly observed a powerful galactic wind that may explain why some of the universe's earliest massive galaxies shut down star formation far sooner than expected. This "galaxy-killing" outflow, driven by cosmic mergers, appears to strip galaxies of the gas needed to form new stars.
According to the research, the wind originates from the collision of two massive galaxies in the early universe. The merger triggers a burst of star formation that also expels vast quantities of gas, effectively choking off the galaxy's ability to continue birthing stars. The observations provide the first direct evidence linking merger-driven winds to the premature quenching of star formation in early galaxies.
The finding challenges existing models of galaxy evolution, which typically predict that massive galaxies form stars for billions of years. Instead, these new data suggest some galaxies burned bright and died young. The wind's velocity and composition were measured using ALMA's sensitivity to cold gas and JWST's infrared capabilities, offering a multi-wavelength view of the phenomenon.
Cosmologists have long puzzled over the existence of massive, quiescent galaxies in the early universe. The study suggests that the very mergers that build up these galaxies may also seal their fate. By expelling the raw material for stars, these winds transform once-active galaxies into "red and dead" relics far earlier than previously thought.
While the observations are compelling, the sample size remains small, and it is unclear how common such merger-driven winds are in the early universe. Further surveys with JWST and next-generation telescopes will be needed to determine whether this mechanism is a universal phenomenon or a rare exception in galactic evolution.