The Effects of Cosmic-Ray Diffusion and Radiative Cooling on the Galactic Wind from the Milky Way

TL;DR

This study investigates how cosmic-ray diffusion and radiative cooling influence the structure of the Milky Way's galactic wind, revealing their combined effects on wind launching and properties.

Contribution

It provides a comprehensive steady-state analysis of galactic wind solutions considering both cosmic-ray diffusion and radiative cooling effects, which were previously studied separately.

Findings

Cosmic-ray pressure effects depend on the Alfvén Mach number.

Wind mass flux is primarily influenced by thermal pressure.

Galactic wind solutions can reach heights of about 300 kpc, contributing to metal pollution.

Abstract

The effects of cosmic-ray diffusion and radiative cooling on the structure of the Galactic wind are studied using a steady state approximation. It is known that realistic cooling processes suppress the wind from launching. The effects of cosmic-ray diffusion are also supposed to be unfavorable for launching the wind. Both of these effects have not been studied simultaneously in a steady-state approximation of the wind. We find 327,254 solutions of the steady-state Galactic wind and confirm that: the effect of cosmic-ray pressure depends on the Alfv{\'e}n Mach number, the mass flux carried by the wind does not depend on the cosmic-ray pressure directly (but depends on the thermal pressure), and the typical conditions found in the Galaxy may correspond to the wind solution that provides metal polluted matters at a height of $\sim300$~kpc from the disk.