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