JWST Finds Ancient Jellyfish Galaxy
A jellyfish galaxy 8.5 billion light-years away shows ram-pressure stripping when the universe was only 5.5 billion years old. This implies faster large-scale structure formation than predicted, with environmental turbulence shaping galaxies much earlier than expected.
This newly identified jellyfish galaxy is officially designated COSMOS2020-635829. A team of astrophysicists from the University of Waterloo spotted the galaxy in deep-space data from the JWST while studying the Cosmic Evolution Survey Deep field, or COSMOS field. Their findings were published in The Astrophysical Journal. Ram-pressure stripping creates the "tentacles" of a jellyfish galaxy. This occurs when a galaxy moves through the hot, dense gas within a galaxy cluster, and the resulting pressure acts like a powerful wind, stripping the galaxy's own gas out from behind it. These long, flowing streams of gas are where new stars are born. The key surprise is that galaxy clusters 8.5 billion years ago were not thought to be dense enough to create the intense pressure required for this process. The discovery of COSMOS2020-635829 suggests that the environment of early galaxy clusters was already harsh and capable of violently altering galaxy evolution. This observation challenges previous assumptions about how and when large-scale structures in the universe formed. The presence of such a mature-looking ram-pressure stripping event so early in cosmic history implies that the vast clusters of galaxies we see today may have developed much more rapidly than models have previously suggested.
