Contributed Talk - Splinter ISM

Friday, 15 September 2023, 16:55   (H 3006)

Gas kinematics and multiphase galactic outflows of the simulated ISM

T.-E. Rathjen, T. Naab, S. Walch, D. Seifried, P. Girichidis, R. Wünsch
Universität zu Köln, Max-Planck Institut für Astrophysik, Universität Heidelberg, Czech Academy of Sciences

Galactic outflows are unambiguously influential in shaping the evolution of galaxies and could be a primary agent in the regulation of star formation. Understanding the multiphase nature, the kinematic structure, and the magnitude of galactic outflows is imperative to inform subgrid models for larger-scale cosmological simulations and successfully interpret observations. Within the SILCC project simulation framework, we are utilising highly sophisticated magnetohydrodynamics (MHD) simulations of the turbulent and multiphase interstellar medium (ISM) to model the origin of those galactic outflows and investigate the main agents which launch them. We are incorporating all major thermal and non-thermal ISM processes and stellar feedback channels like non-equilibrium chemistry, self-gravity, stellar winds from massive stars, hydrogen-ionising UV radiation, core-collapse supernovae and acceleration and anisotropic diffusion of cosmic rays (CRs). We investigate the impact of those ISM processes with a special emphasis on the effects of CRs on the capability to launch galactic outflows and find that the gas phase structure of the outflowing gas changes to a three-phase medium (hot, warm and cold, T < 300 K) with CRs as compared to a mostly warm-hot medium in the case without CRs. The impact of CRs on mass loading factors decreases for higher gas surface density simulations and the mass loading factors of the CR-supported outflows are of order unity independent of the star formation rate surface density. Similar to observations, vertical velocity dispersions of the warm ionised medium (WIM) and the cold neutral medium (CNM) correlate with the star formation rate as power-law with a slope of ~0.20. In the absence of stellar feedback, we find no correlation, which suggests that stellar feedback plays a crucial role in driving turbulence in the ISM.