Astronomers have discovered a “galaxy-killing wind” that may explain why there are far more massive “dead” galaxies than expected in the early universe. This wind, powered by cosmic collisions between galaxies, could quickly blow away all the fuel for new stars, leaving a galaxy on the brink of death and helping to solve one of the biggest mysteries in modern astrophysics.
The theory is much simpler than some of the other explanations put forward since 2022, when the James Webb Space Telescope (JWST) gave scientists their first clear glimpse of the early universe. Among them was the idea that dark energy may have been stronger in the early universe than current theories predict, allowing galaxies to grow and die faster.
Researchers behind the new study, published on June 10 in Monthly Notices of the Royal Astronomical Society, used JWST to show that galaxy-killing winds can be powered by the same intense star formation that causes galaxies to grow rapidly, explaining why these early galaxies live fast and die young.
“Dense regions of the universe are like very active cities,” said lead author Dr. Rebecca Davies of Swinburne University of Technology in Melbourne, who carried out the study with Associate Professor Deanne Fisher.
Galaxy winds have long been considered prime suspects in the deaths of massive galaxies, but observational evidence was lacking. Using JWST and the Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope, the Swinburne team imaged a galaxy 1 billion years after the Big Bang in the midst of a rapid growth spurt.
This galaxy, called CRISTAL-02, is forming stars twice as fast as other similarly sized galaxies. The extremely sensitive observations revealed a huge plume of cold gas extending far from CRISTAL-02. This plume is almost as long as the galaxy itself, which is a telltale sign that gas is being driven out of the galaxy.
CRISTAL-02 is not a single galaxy, but multiple galaxies in the final stages of a cosmic collision. During such collisions, gas funnels toward the galaxy centers, triggering strong bursts of star formation.
Dr. Davies believes that other galaxies will likely face a similar fate to CRISTAL-02, undergoing frenzied bursts of star formation followed by powerful winds that lead them to their deaths.
“Almost half of early massive galaxies are interacting with other nearby galaxies, suggesting this isn’t a quirk but a widespread cosmic phenomenon,” she said. “CRISTAL-02 offers a natural solution to the mystery of why these massive galaxies live fast and die young.” (Phys.org)
