Abstract

Contributed Talk - Splinter StarFormation   (MW-1250)

Cosmic ray feedback across scales: from star formation to galaxy evolution

Christoph Pfrommer
Leibniz-Institut für Astrophysik Potsdam (AIP)

Feedback processes play a central role in shaping the structure and evolution of galaxies. Baryonic matter cycles through stars, which return energy to the interstellar medium (ISM) via supernova explosions, thereby driving multiphase galactic winds. Cosmic rays (CRs), accelerated in supernova remnants, represent a key component of this feedback. While CRs can significantly contribute to wind driving, their overall impact is highly sensitive to the underlying CR transport model. First, I present high-resolution “tallbox” simulations of a galactic disk patch performed with the moving-mesh magnetohydrodynamics code Arepo, incorporating a range of CR transport prescriptions as well as the CRISP non-equilibrium thermochemistry model. We investigate how CR feedback influences both star formation and the properties of multiphase outflows. Our results show that CR-driven winds can efficiently sustain large-scale outflows, whereas purely thermal winds dissipate most of their energy within ~3 kpc above the disk midplane. We further demonstrate that the steady-state structure of the wind is strongly dependent on the chosen CR transport model. In particular, a model including CR advection, streaming, diffusion, and nonlinear Landau damping produces especially strong feedback. When ion–neutral damping is additionally included, CRs partially decouple from the cold ISM, leading to a reduced impact on the star formation rate while still maintaining efficient feedback on galactic scales. This picture is extended to global simulations of CR-driven galactic winds in star forming galaxies, demonstrating the importance of CR feedback on the formation of stars, star clusters, and galaxy evolution.