The Spatially Resolved Dynamics of Dusty Starburst Galaxies in a z ~ 0.4
  Cluster: Beginning the Transition from Spirals to S0s
  To investigate what drives the reversal of the morphology-density relation at
intermediate/high redshift, we present a multi-wavelength analysis of 27 dusty
starburst galaxies in the massive cluster Cl 0024+17 at z = 0.4. We combine
H-alpha dynamical maps from the VLT/FLAMES multi-IFU system with far-infrared
imaging using Herschel SPIRE and millimetre spectroscopy from IRAM/NOEMA, in
order to measure the dynamics, star formation rates and gas masses of this
sample. Most galaxies appear to be rotationally supported, with a median ratio
of rotational support to line-of-sight velocity dispersion v/sigma ~ 5 +/- 2,
and specific angular momentum lambda_R = 0.83 +/- 0.06 - comparable to field
spirals of a similar mass at this redshift. The star formation rates of 3 - 26
M_solar/yr and average 12 CO derived gas mass of 1 x 10^10 M_solar suggest gas
depletion timescales of ~ 1Gyr (~ 0.25 of the cluster crossing time). We derive
characteristic dust temperatures (mean T_dust = 26 +/- 1 K) consistent with
local galaxies of similar far-infrared luminosity, suggesting that the low
density gas is yet to be stripped. Taken together, these results suggest that
these starbursts have only recently accreted from the field, with star
formation rates likely enhanced due to the effects of ram pressure. In order to
make the transition to cluster S0s these galaxies must lose ~ 40% of their
specific angular momentum. We suggest this must occur > 1 Gyr later, after the
molecular gas has been depleted and/or stripped, via multiple tidal
interactions with other cluster members.
