Lyman Continuum-Driven Superwind in Green Pea Analog Mrk 71

Abstract

Mrk 71 is the closest Green Pea analog, dominated by Knot A, a young, metal-poor super star cluster that is a strong candidate Lyman continuum (LyC) emitter. Broad, faint emission-line wings tracing > 3000 km/s gas of unknown origin have been observed in Mrk 71. We analyze spatially-resolved [O III] and Hα emission-line profiles obtained with GMOS-N IFU, and find that the broad wings a) exhibit a wind kinematic structure originating from Knot A; b) have symmetric, power-law line profiles; and c) cannot be explained by supernovae or stellar winds. On the other hand, the radiation energy, ionization parameter, and stellar surface density, associated with Knot A signal radiation-dominated feedback. We show that a clumpy, LyC and/or Lyα-driven superwind from Knot A can reproduce the observed broad wings. Our finding thus strongly suggests that LyC escapes from Knot A, which may also occur in other Green Pea LyC emitters.