Cosmic ray driven galactic winds

TL;DR

This paper reviews the current understanding of cosmic ray-driven galactic winds, emphasizing their complex physics, the role of cosmic ray transport, and the challenges in modeling these phenomena.

Contribution

It provides a comprehensive summary of the physics behind cosmic ray-driven winds and discusses future directions for research in this field.

Findings

Cosmic rays can drive galactic winds in Milky Way-like galaxies.

The formation of these winds involves complex, non-linear, multiscale physics.

Current models face significant theoretical challenges that need addressing.

Abstract

Galactic winds constitute a primary feedback process in the ecology and evolution of galaxies. They are ubiquitously observed and exhibit a rich phenomenology, whose origin is actively investigated both theoretically and observationally. Cosmic rays have been widely recognized as a possible driving agent of galactic winds, especially in Milky-Way like galaxies. The formation of cosmic ray-driven winds is intimately connected with the microphysics of the cosmic ray transport in galaxies, making it an intrinsically non-linear and multiscale phenomenon. In this complex interplay the cosmic ray distribution affects the wind launching and, in turns, is shaped by the presence of winds. In this review we summarize the present knowledge of the physics of cosmic rays involved in the wind formation and of the wind hydrodynamics. We also discuss the theoretical difficulties connected with the study of cosmic ray-driven winds and possible future improvements and directions.