Super star cluster feedback driving ionization, shocks and outflows in
  the halo of the nearby starburst ESO 338-IG04
  Stellar feedback strongly affects the interstellar medium (ISM) of galaxies.
Stellar feedback in the first galaxies likely plays a major role in enabling
the escape of LyC photons, which contribute to the re-ionization of the
Universe. Nearby starburst galaxies serve as local analogues allowing for a
spatially resolved assessment of the feedback processes in these galaxies. We
characterize the feedback effects from the star clusters in the local
high-redshift analogue ESO 338-IG04 on the ISM and compare the results with the
properties of the most massive clusters. We use high quality VLT/MUSE optical
integral field data to derive the physical properties of the ISM such as
ionization, density, shocks, and perform new fitting of the spectral energy
distributions of the brightest clusters in ESO 338-IG04 from HST imaging. ESO
338-IG04 has a large ionized halo which we detect to a distance of 9 kpc. We
identify 4 Wolf-Rayet (WR) clusters based on the blue and red WR bump. We
follow previously identified ionization cones and find that the ionization of
the halo increases with distance. Analysis of the galaxy kinematics shows two
complex outflows driven by the numerous young clusters in the galaxy. We find a
ring of shocked emission traced by an enhanced [OI]/H$\alpha$ ratio surrounding
the starburst and at the end of the outflow. Finally we detect nitrogen
enriched gas associated with the outflow, likely caused by the WR stars in the
massive star clusters. Photo-ionization dominates the central starburst and
sets the ionization structure of the entire halo, resulting in a density
bounded halo, facilitating the escape of LyC photons. Outside the central
starburst, shocks triggered by an expanding super bubble become important. The
shocks at the end of the outflow suggest interaction between the hot outflowing
material and the more quiescent halo gas.
