We report the discovery of COSMOS2020-635829 as a candidate jellyfish galaxy undergoing ram pressure stripping in a (proto)cluster at z>1. High-resolution imaging from the James Webb Space Telescope reveals a symmetric stellar disk coupled to a unilateral tail of star-forming knots to the south. Using Gemini GMOS IFU observations, we show that these extra-planar continuum sources are embedded within an ionized gas tail that is kinematically connected to the disk of COSMOS2020-635829. If confirmed, this represents the highest-redshift discovery of a ram pressure stripped ionized gas tail. The tail sources are characterized by extremely young stellar populations (≲100Myr), have stellar masses of ∼108M⊙, and star formation rates of 0.1–1M⊙yr−1. This work shows that ram pressure stripping can potentially perturb group and cluster galaxies at z>1 and may contribute to environmental quenching even near Cosmic Noon.
@article{arxiv.2506.14117,
title = {JWST Reveals a Candidate Jellyfish Galaxy at z=1.156},
author = {Ian D. Roberts and Michael L. Balogh and Visal Sok and Adam Muzzin and Michael J. Hudson and Pascale Jablonka},
journal= {arXiv preprint arXiv:2506.14117},
year = {2026}
}