MUSE sneaks a peek at extreme ram-pressure stripping events. I. A kinematic study of the archetypal galaxy ESO137-001

TL;DR

This study uses MUSE observations to analyze the ram-pressure stripping of galaxy ESO137-001 in the Norma cluster, revealing how gas is removed and how the tail's kinematics inform about the galaxy's motion and interaction with the cluster medium.

Contribution

First detailed kinematic analysis of ram-pressure stripping in ESO137-001 using MUSE, showing gas removal mechanisms and tail dynamics in a cluster environment.

Findings

Ram-pressure has stripped the outer disk gas from ESO137-001.

The gas tail retains disk rotation imprint up to 20 kpc.

Turbulence increases beyond 20 kpc in the tail.

Abstract

We present MUSE observations of ESO137-001, a spiral galaxy infalling towards the center of the massive Norma cluster at z~0.0162. During the high-velocity encounter of ESO137-001 with the intracluster medium, a dramatic ram-pressure stripping event gives rise to an extended gaseous tail, traced by our MUSE observations to >30 kpc from the galaxy center. By studying the H-alpha surface brightness and kinematics in tandem with the stellar velocity field, we conclude that ram pressure has completely removed the interstellar medium from the outer disk, while the primary tail is still fed by gas from the inner regions. Gravitational interactions do not appear to be a primary mechanism for gas removal. The stripped gas retains the imprint of the disk rotational velocity to ~20 kpc downstream, without a significant gradient along the tail, which suggests that ESO137-001 is fast moving along a radial orbit in the plane of the sky. Conversely, beyond ~20 kpc, a greater degree of turbulence is seen, with velocity dispersion up to >100 km/s. For a model-dependent infall velocity of ~3000 km/s, we conclude that the transition from laminar to turbulent flow in the tail occurs on timescales >6.5 Myr. Our work demonstrates the terrific potential of MUSE for detailed studies of how ram-pressure stripping operates on small scales, providing a deep understanding of how galaxies interact with the dense plasma of the cluster environment.