Abstract
We present a hydrodynamical simulation of the turbulent, magnetized,
supernova-driven interstellar medium (ISM) in a stratified box that dynamically
couples the injection and evolution of cosmic rays (CRs) and a self-consistent
evolution of the chemical composition. CRs are treated as a relativistic fluid
in the advection-diffusion approximation. The thermodynamic evolution of the
gas is computed using a chemical network that follows the abundances of H+, H,
H2, CO, C+, and free electrons and includes (self-)shielding of the gas and
dust. We find that CRs perceptibly thicken the disk with the heights of 90%
(70%) enclosed mass reaching ~1.5 kpc (~0.2 kpc). The simulations indicate that
CRs alone can launch and sustain strong outflows of atomic and ionized gas with
mass loading factors of order unity, even in solar neighbourhood conditions and
with a CR energy injection per supernova (SN) of 10^50 erg, 10% of the fiducial
thermal energy of a SN. The CR-driven outflows have moderate launching
velocities close to the midplane (~100 km/s) and are denser (\rho~1e-24 - 1e-26
g/cm^3), smoother and colder than the (thermal) SN-driven winds. The
simulations support the importance of CRs for setting the vertical structure of
the disk as well as the driving of winds.
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