Emission-line Wings Driven by Lyman Continuum in the Green Pea Analog
  Mrk 71
  We propose that the origin of faint, broad emission-line wings in the Green
Pea (GP) analog Mrk 71 is a clumpy, LyC and/or Ly$\alpha$-driven superwind. Our
spatially-resolved analysis of Gemini-N/GMOS-IFU observations shows that these
line wings with terminal velocity $>3000~\rm{km~s^{-1}}$ originate from the
super star cluster (SSC) Knot A, and propagate to large radii. The object's
observed ionization parameter and stellar surface density are close to their
theoretical maxima, and radiation pressure dominates over gas pressure.
Together with a lack of evidence for supernova feedback, these imply a
radiation-dominated environment. We demonstrate that a clumpy, radiation-driven
superwind from Knot A is a viable model for generating the extreme velocities,
and in particular, that Lyman continuum and/or Ly$\alpha$ opacity must be
responsible. We find that the Mrk 71 broad wings are best fitted with power
laws, as are those of a representative extreme GP and a luminous blue variable
star, albeit with different slopes. This suggests that they may share a common
wind-acceleration mechanism. We propose that high-velocity, power-law wings may
be a distinctive signature of radiation feedback, and of radiatively-driven
winds, in particular.
