James Webb: A galaxy killer wind has been spotted by the space telescope

The James Webb Space Telescope has uncovered evidence of powerful stellar winds capable of effectively "killing" galaxies by preventing new star formation, according to a study published on June 10 in the *Monthly Notices of the Royal Astronomical Society*. The research, led by an international team of scientists, provides direct observational support for a long-theorized process where intense galactic winds can suppress star birth in early stages of the universe.

The study focused on the CRISTAL-02 galaxy system, which existed just one billion years after the Big Bang. This system represents the final phase of a multi-galaxy collision, involving two merging galaxies. Observations were conducted using both the James Webb Space Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile. These tools allowed researchers to detect a massive gas cloud within the CRISTAL-02 system, nearly as long as the entire galaxy itself, moving away from space at speeds exceeding hundreds of kilometers per second.

This gas cloud, estimated to have a mass of about 1.5 billion times that of the Sun, appears to be driven by intense stellar winds generated by rapid bursts of star formation and the subsequent deaths of massive stars. When galaxies collide, vast clouds of interstellar gas and dust interact, leading to the creation of new stars, including some of extremely high mass. However, these massive stars typically explode as supernovae within a few million years, releasing powerful radioactive winds.

These winds can disrupt further star formation by heating and dispersing cold molecular gas before it can condense into dense regions necessary for the birth of new stars. According to the study, this mechanism might explain why many early galaxies experienced rapid decline in their ability to form new stars.

Rebecca Davies, an astrophysicist at Australia's Swinburne University of Technology and lead author of the study, noted that the winds in the CRISTAL-02 galaxy are so strong they expel material twice as fast as the rate at which the galaxy could create new stars. In this system, approximately 260 solar-mass stars are formed each year—three times faster than typical galaxies of similar size and age. However, the galaxy also loses over 500 solar masses annually due to these winds, a loss rate ten times higher than that seen in typical large galaxies.

Andreas Faisst, an observational astronomer at Caltech and co-author of the study, emphasized that previous knowledge about how star formation ceased in early galaxies was limited. He stated that this research directly demonstrates the process in action, offering insights into the mechanisms behind galactic aging—the gradual decline in star-forming activity.

If the outflow continues, the CRISTAL-02 galaxy will exhaust its supply of gas needed for star formation within less than 100 million years, a relatively brief period in astronomical terms. This finding highlights the dynamic nature of galaxy evolution, showing how interactions between galaxies can significantly alter their future trajectories.

The study contributes to understanding the broader context of galactic evolution, particularly how early massive galaxies interacted with neighboring systems. It suggests that such interactions played a crucial role in shaping the structure and development of the universe shortly after the Big Bang. As more data becomes available from advanced telescopes like the James Webb, astronomers expect to uncover additional instances of similar phenomena, refining our understanding of cosmic processes that govern the life cycles of galaxies.