# GASP II. A MUSE view of extreme ram-pressure stripping along the line of sight: kinematics of the jellyfish galaxy JO201

## TL;DR

This study uses MUSE observations to analyze the kinematics of galaxy JO201, revealing how intense ram-pressure stripping along the line of sight causes significant gas loss, disk disturbance, and tail formation in a cluster environment.

## Contribution

It provides the first detailed kinematic analysis of JO201's RPS effects along the line of sight, highlighting the gas loss and tail formation mechanisms.

## Key findings

- JO201 is moving at supersonic speeds through Abell 85's medium.
- Approximately 50% of gas has been stripped from JO201.
- Gas tails extend up to 50 kpc with distinct kinematic properties.

## Abstract

This paper presents a spatially-resolved kinematic study of the jellyfish galaxy JO201, one of the most spectacular cases of ram-pressure stripping (RPS) in the GASP (GAs Stripping Phenomena in Galaxies with MUSE) survey. By studying the environment of JO201, we find that it is moving through the dense intra-cluster medium of Abell 85 at supersonic speeds along our line of sight, and that it is likely accompanied by a small group of galaxies. Given the density of the intra-cluster medium and the galaxy's mass, projected position and velocity within the cluster, we estimate that JO201 must so far have lost ~50% of its gas during infall via RPS. The MUSE data indeed reveal a smooth stellar disk, accompanied by large projected tails of ionised (Halpha) gas, composed of kinematically cold (velocity dispersion <40km/s) star-forming knots and very warm (>100km/s) diffuse emission which extend out to at least ~50 kpc from the galaxy centre. The ionised Halpha-emitting gas in the disk rotates with the stars out to ~6 kpc but in the disk outskirts becomes increasingly redshifted with respect to the (undisturbed) stellar disk. The observed disturbances are consistent with the presence of gas trailing behind the stellar component, resulting from intense face-on RPS happening along the line of sight. Our kinematic analysis is consistent with the estimated fraction of lost gas, and reveals that stripping of the disk happens outside-in, causing shock heating and gas compression in the stripped tails.