Astronomers using the James Webb Space Telescope have identified the farthest jellyfish galaxy observed to date, located at a redshift of z=1.156. This galaxy, viewed as it appeared 8.5 billion years ago, features trailing streams of gas and young stars shaped by ram-pressure stripping in a dense cluster. The finding suggests that early universe galaxy clusters were more turbulent than previously thought.
Researchers from the University of Waterloo announced the discovery of a jellyfish galaxy in deep space, observed through data from the James Webb Space Telescope (JWST). The galaxy, which resembles a cosmic oddity with long, tentacle-like trails of gas and newborn stars, was spotted while racing through a crowded galaxy cluster. These trails form due to ram-pressure stripping, where hot gas in the cluster acts like a headwind, pulling the galaxy's gas backward.
The observation captures the galaxy at z=1.156, meaning its light has traveled 8.5 billion years to Earth, offering a view into the universe's younger phase. It was found in the COSMOS field, a well-studied region selected for its clear sightlines away from Milky Way interference. "We were looking through a large amount of data from this well-studied region in the sky with the hopes of spotting jellyfish galaxies that haven't been studied before," said Dr. Ian Roberts, Banting Postdoctoral Fellow at the Waterloo Centre for Astrophysics. "Early on in our search of the JWST data, we spotted a distant, undocumented jellyfish galaxy that sparked immediate interest."
The galaxy maintains a typical disk shape, but bright blue clumps along its streams indicate young stars forming in the stripped gas, outside the main body. This aligns with expectations for ram-pressure stripping effects. The discovery challenges prior views that galaxy clusters were still forming at this epoch and that such stripping was uncommon. "The first is that cluster environments were already harsh enough to strip galaxies, and the second is that galaxy clusters may strongly alter galaxy properties earlier than expected," Roberts explained. "This data provides us with rare insight into how galaxies were transformed in the early universe."
The team has requested more JWST time for deeper study. The research, titled "JWST Reveals a Candidate Jellyfish Galaxy at z=1.156," appears in The Astrophysical Journal.