Particle acceleration in galactic wind bubbles

TL;DR

This paper models particle acceleration at the termination shocks of galactic wind bubbles, exploring their potential to produce cosmic rays, gamma rays, and neutrinos, and analyzing different wind powering mechanisms.

Contribution

It introduces a new model for particle acceleration at wind termination shocks considering various wind engines and assesses their multi-messenger astrophysical signals.

Findings

Wind termination shocks can efficiently accelerate particles.

Galactic winds could be sources of high-energy cosmic rays.

Potential detection of gamma rays and neutrinos from these processes.

Abstract

Winds are ubiquitous in galaxies and often feature bubble structures. These wind bubbles are characterized by an external forward shock expanding in the surrounding medium and a wind termination shock separating the cool and fast wind from the hot shocked wind. While the forward shock could not be able to accelerate particles efficiently for a long time, at the wind termination shock the necessary conditions for efficient acceleration may be present. We develop a model for particle acceleration at the termination shock of such bubbles analysing the consequences of different possible engines powering the wind. We finally explore the multi-messenger potential of galactic winds in terms of escaping cosmic rays and high-energy gamma rays and neutrinos produced through hadronic interactions.