Large-scale galactic winds driven by stellar feedback are one phenomenon that influences the dynamical and chemical evolution of a galaxy, redistributing material throughout the circumgalatic medium. Non-thermal feedback from galactic cosmic rays (CRs) – high-energy charged particles accelerated in supernovae and young stars – can impact the efficiency of wind driving. The streaming instability limits the speed at which they can escape. However, in the presence of turbulence, the streaming instability is subject to suppression that depends on the magnetization of turbulence given by its Alfvén Mach number. While previous simulations that relied on a simplified model of CR transport have shown that super-Alfvénic streaming of CRs enhances galactic winds, in this paper we take into account a realistic model of streaming suppression. We perform three-dimensional magnetohydrodynamic simulations of a section of a galactic disc and find that turbulent damping dependent on local magnetization of turbulent interstellar medium (ISM) leads to more spatially extended gas and CR distributions compared to the earlier streaming calculations, and that scale heights of these distributions increase for stronger turbulence. Our results indicate that the star formation rate increases with the level of turbulence in the ISM. We also find that the instantaneous wind mass loading is sensitive to local streaming physics with the mass loading dropping significantly as the strength of turbulence increases.
In a seminal paper, Parker showed the vertical stratification of the interstellar medium (ISM) is unstable if magnetic fields and cosmic rays provide too large a fraction of pressure support. Cosmic ray acceleration is linked to star formation, so Parker’s instability and its nonlinear outcomes are a type of star formation feedback. Numerical simulations have shown the instability can significantly restructure the ISM, thinning the thermal gas layer and thickening the magnetic field and cosmic ray layer. However, the timescale on which this occurs is rather long (∼0.4 Gyr). Furthermore, the conditions for instability depend on the model adopted for cosmic ray transport. In this work, we connect the instability and feedback problems by examining the effect of a single, spatially and temporally localized cosmic ray injection on the ISM over ∼1 kpc3scales. We perform cosmic ray magnetohydrodynamic simulations using the
- Award ID(s):
- 2007323
- NSF-PAR ID:
- 10429640
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 951
- Issue:
- 2
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- Article No. 99
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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