The baryon cycle of Seven Dwarfs with superbubble feedback
  We present results from a high-resolution, cosmological, $\Lambda$CDM
simulation of a group of field dwarf galaxies with the "superbubble" model for
clustered SN feedback, accounting for thermal conduction and cold gas
evaporation. The initial conditions and the galaxy formation physics, other
than SN feedback, are the same as in Shen et al. (2014). The simulated luminous
galaxies have blue colors, low star formation efficiencies and metallicities,
and high cold gas content, reproducing the observed scaling relations of dwarfs
in the Local Volume. Bursty star formation histories and superbubble-driven
outflows lead to the formation of kpc-size DM cores when stellar masses reaches
$M_{*} > 10^6$ $M_{\odot}$, similar to previous findings. However, the
superbubble model appears more effective in destroying DM cusps than the
previously adopted "blastwave" model, reflecting a higher coupling efficiency
of SN energy with the ISM. On larger scale, superbubble-driven outflows have a
more moderate impact: galaxies have higher gas content, more extended stellar
disks, and a smaller metal-enriched region in the CGM. The two halos with
$M_{vir} \sim 10^9$ $M_{\odot}$, which formed ultra-faint dwarf galaxies in
Shen et al. (2014), remain dark due to the different impact of metal-enriched
galactic winds from two nearby luminous galaxies. The column density
distributions of H I, Si II, C IV and O VI are in agreement with recent
observations of CGM around isolated dwarfs. While H I is ubiquitous with a
covering fraction of unity within the CGM, Si II and C IV are less extended. O
VI is more extended, but its mass is only 11% of the total CGM oxygen budget,
as the diffuse CGM is highly ionised by the UVB. Superbubble feedback produces
C IV and O VI an order of magnitude higher column densities than those with
blastwave feedback. The CGM and DM cores are most sensitive probes of feedback
mechanisms.
