SF-01-0012

Introducing TIGRESS-NCR: Co-regulation of Multiphase ISM and Star Formation Rates

Kim Chang-Goo, Kim Jeong-Gyu, Munan Gong, Eve C. Ostriker

The energy and momentum injected by young massive stars are the primary source of heating and turbulence in the multiphase interstellar medium (ISM). The thermal and dynamical state of the ISM and galactic environment in turn determine the amount of gas susceptible to gravitational collapse. Any successful model for star-forming ISM needs to account for this self-regulation process driven by stellar feedback. The TIGRESS (Three-phase Interstellar Medium in Galaxies Resolving Evolution with Star Formation and Supernova Feedback) numerical framework models a patch of differentially rotating galactic disk with self-consistent star formation and feedback and has been successfully applied to study star formation and various aspects of ISM physics in different environments. In this work, we present the TIGRESS-NCR (Non-equilibrium Cooling and Radiation) framework that includes explicit treatment of ISM photochemistry coupled with UV radiation transfer. We use the adaptive ray tracing method to follow propagation of UV radiation and its attenuation by gas and dust. We track time-dependent evolution of hydrogen species and steady-state abundances of C-, O-bearing species to capture thermodynamics of all ISM phases. We run simulations representing typical conditions of normal star-forming galaxies and analyze their ISM phase distributions, finding good agreement with observational constraints. We also demonstrate that star formation rate is proportional to the total midplane pressure (and vertical weight), and measure feedback yields, namely, the ratios between pressure components (thermal, turbulent, and magnetic) and star formation rate. We will use the TIGRESS-NCR framework to explore star-forming ISM in a wide range of galactic conditions, including low-metallicity environments.