Cooler and smoother -- the impact of cosmic rays on the phase structure
  of galactic outflows
  We investigate the impact of cosmic rays (CRs) on galactic outflows from a
multi-phase interstellar medium with solar neighbourhood conditions. The
three-dimensional magneto-hydrodynamical simulations include CRs as a
relativistic fluid in the advection-diffusion approximation. The thermal and
chemical state of the ISM is computed with a non-equilibrium chemical network.
We find that CRs (injected with 10 \% of the supernova energy) efficiently
support the launching of outflows and strongly affect their phase structure.
Outflows leaving the midplane are denser ($\rho \sim
10^{-26}\,\mathrm{g\,cm}^{-3}$), colder ($\sim 10^4\,\mathrm{K}$), and slower
($\sim 30\,\mathrm{km\,s}^{-1}$) if CRs are considered in addition to thermal
SNe. The CR supported outflows are also smoother, in particular at larger
heights ($> 1\,\mathrm{kpc}$ above the midplane) without the direct impact of
SN explosions. Approximately $5\% - 25\%$ of the injected CR energy is lost via
hadronic cooling. Smaller diffusion coefficients lead to slightly larger
hadronic losses but allow for steeper CR pressure gradients, stronger outflows
and larger accelerations. Up to a height of $z \sim1\,\mathrm{kpc}$ there are
large volumes in approximate pressure equilibrium between thermal and CR
component. At larger altitudes the CR pressure is $10-100$ times as large as
the thermal counterpart. More than $\sim 1\,\mathrm{kpc}$ away from the
midplane, CRs provide the dominant gas acceleration mechanism.
