Kinematics and Optical Depth in the Green Peas: Suppressed Superwinds in
  Candidate LyC Emitters
  By clearing neutral gas away from a young starburst, superwinds may regulate
the escape of Lyman continuum (LyC) photons from star-forming galaxies.
However, models predict that superwinds may not launch in the most extreme,
compact starbursts. We explore the role of outflows in generating low optical
depths in the Green Peas (GPs), the only known star-forming population with
several confirmed and candidate LyC-leaking galaxies. With Hubble Space
Telescope UV spectra of 25 low-redshift GPs, including new observations of 13
of the most highly ionized GPs, we compare the kinematics of UV absorption
lines with indirect HI optical depth diagnostics: Ly-alpha escape fraction,
Ly-alpha peak separation, or low-ionization absorption line equivalent width.
The data suggest that high ionization kinematics tracing superwind activity may
correlate with low optical depth in some objects. However, the most extreme
GPs, including many of the best candidate LyC emitters with weak low-ionization
absorption and strong, narrow Ly-alpha profiles, show the lowest velocities.
These results are consistent with models for suppressed superwinds, which
suggests that outflows may not be the only cause of LyC escape from galaxies.
