Publications
Home
Centers & Programs
Quantum Universe
Publications
- Title
- Cosmic-Ray Feedback in Galactic Disks: Star Formation, Cosmic-Ray Transport, and Multiphase Outflows in Tigress plus plus Simulations
- KIAS Author
- Kim, Jeong-Gyu
- Journal
- ASTROPHYSICAL JOURNAL, 2026
- Archive
-
- Abstract
- We present new simulations of local star-forming disks that self-consistently evolve cosmic rays (CRs) and multiphase gas using Tigress++. To isolate the role of CRs, we conduct paired simulations under solar-neighborhood conditions: a magnetohydrodynamics (MHD) model following the standard Tigress-classic framework with far-UV heating and supernova (SN) feedback from star clusters formed via gravitational collapse, and a CR + MHD (CRMHD) model in which an additional 10% of each SN's energy is injected as CRs. These CRs are transported anisotropically along magnetic field lines via a two-moment solver, with the CR scattering rate set by balancing Alfv & eacute;n-wave growth and damping based on the self-confinement paradigm. The CRMHD model develops a characteristic two-zone vertical CR profile: uniform pressure in the diffusion-dominated, high-density midplane gas, and an exponential atmosphere shaped primarily by advection and streaming in low-density extraplanar gas. The CR pressure is comparable to the total thermal gas pressure in the midplane, but is too uniform to affect gas dynamics, leaving the star formation rates unchanged. In contrast, the vertical CR pressure gradient at divided by z divided by greater than or similar to 1 kpc accelerates warm outflowing gas, resulting in an approximately 4 times higher mass loading factor than in the MHD model. CR-gas interactions increase the CR energy near the midplane through compressional work, while CR streaming heats low-density warm-hot gas. Tigress++ opens a path toward investigating CR transport and CR-regulated interstellar medium and outflow dynamics at high resolution across diverse galactic environments.
