James Webb Telescope Identifies Distant Jellyfish Galaxy

Astronomers have identified a jellyfish galaxy, designated COSMOS2020-635829, approximately 8.5 billion light-years from Earth, using the James Webb Space Telescope (JWST). This discovery offers valuable insights into galaxy evolution during the early universe.

Jellyfish galaxies are characterized by elongated streams of gas and stars trailing behind them, resembling jellyfish tentacles. These features result from ram-pressure stripping, a process where a galaxy moves rapidly through the dense gas of a galaxy cluster, causing its own gas to be pushed out and form trailing streams.

The research team, led by Dr. Ian Roberts from the University of Waterloo, identified COSMOS2020-635829 within the COSMOS field—a well-studied region of the sky. The galaxy exhibits a normal-looking disk with bright blue knots in its trails, indicative of very young stars. The presence of these young stars suggests that star formation is occurring within the stripped gas trails, a phenomenon expected in jellyfish galaxies.

This finding challenges previous assumptions that galaxy clusters in the early universe were not dense enough to induce ram-pressure stripping. The data imply that such environmental effects were already influencing galaxy properties earlier than previously thought, potentially contributing to the development of the large population of inactive galaxies observed in clusters today.

The study detailing this discovery has been published in The Astrophysical Journal.