A Framework for Multiphase Galactic Wind Launching using TIGRESS
  Galactic outflows have density, temperature, and velocity variations at least
as large as that of the multiphase, turbulent interstellar medium (ISM) from
which they originate. We have conducted a suite of parsec-resolution numerical
simulations using the TIGRESS framework, in which outflows emerge as a
consequence of interaction between supernovae (SNe) and the star-forming ISM.
The outflowing gas is characterized by two distinct thermal phases, cool
(T<10^4 K) and hot (T>10^6 K), with most mass carried by the cool phase and
most energy and newly-injected metals carried by the hot phase. Both components
have a broad distribution of outflow velocity, and especially for cool gas this
implies a varying fraction of escaping material depending on the halo
potential. Informed by the TIGRESS results, we develop straightforward analytic
formulae for the joint probability density functions (PDFs) of mass, momentum,
energy, and metal loading as distributions in outflow velocity and sound speed.
The model PDFs have only two parameters, SFR surface density \Sigma_SFR and the
metallicity of the ISM, and fully capture the behavior of the original TIGRESS
simulation PDFs over \Sigma_SFR~(10^{-4},1)M_sun/kpc^2/yr. Employing PDFs from
resolved simulations will enable galaxy formation subgrid model implementations
with wind velocity and temperature (as well as total loading factors) that are
based on theoretical predictions rather than empirical tuning. This is a
critical step to incorporate advances from TIGRESS and other high-resolution
simulations in future cosmological hydrodynamics and semi-analytic galaxy
formation models. We release a python package to prototype our model and to
ease its implementation.
