Astronomers have discovered a powerful “galaxy-killing wind” that may explain one of the biggest mysteries about the early universe: why so many massive galaxies stopped making new stars much sooner than scientists expected.
The discovery suggests that some of the universe’s earliest galaxies may have grown at incredible speed, only to destroy their own ability to keep forming stars.
The research, published in Monthly Notices of the Royal Astronomical Society: Letters, used observations from the James Webb Space Telescope (JWST) and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.
Scientists have been puzzled since JWST began revealing detailed images of the early universe.
They found many large “dead” galaxies—galaxies that had already stopped forming stars only about one billion years after the Big Bang.
According to previous theories, there should not have been enough time for so many massive galaxies to grow and then shut down.
Some researchers even suggested that dark energy may have behaved differently in the early universe, allowing galaxies to evolve much faster than current models predict.
The new study offers a much simpler explanation.
Lead researcher Dr. Rebecca Davies from Swinburne University of Technology and Associate Professor Deanne Fisher found evidence that intense bursts of star formation can create enormous winds that blow away the gas needed to make future stars.
Stars are born from cold gas inside galaxies. When many massive stars form at the same time, they eventually explode as supernovae. These explosions release huge amounts of energy, creating powerful winds that can push gas out of the galaxy. Without enough gas, star formation slows down and eventually stops.
The team focused on a distant object known as CRISTAL-02, which existed about one billion years after the Big Bang. The observations showed that this galaxy is producing stars at about twice the rate of other galaxies of a similar size.
At the same time, the telescopes detected a giant stream of cold gas stretching almost as far as the galaxy itself. This is strong evidence that gas is being blasted out of the galaxy by an extremely powerful wind.
The researchers found that CRISTAL-02 is losing gas about twice as fast as it is creating new stars. If this continues, the galaxy could run out of the fuel needed for star formation in less than 50 million years—a very short time in the life of a galaxy.
The study also revealed that CRISTAL-02 is actually made up of several galaxies that are merging together. During these collisions, large amounts of gas are driven toward the center, triggering intense bursts of star formation. Those same bursts then produce the powerful winds that eventually strip the galaxy of its star-making material.
The researchers believe this process may have been common in the early universe. Since nearly half of massive young galaxies appear to be interacting with nearby galaxies, many could have followed the same pattern—rapid growth followed by a quick shutdown.
If so, these “galaxy-killing winds” may finally explain why so many massive galaxies in the young universe lived fast, burned brightly, and died so early.
Source: KSR.
