Cosmic rays from star clusters

TL;DR

This paper discusses how star clusters, through their massive stars and resulting superbubbles, contribute to cosmic ray acceleration in the galaxy.

Contribution

It highlights the role of star clusters and superbubbles as significant sites for cosmic ray acceleration, emphasizing their impact on the galactic cosmic ray population.

Findings

Superbubbles are formed by collective stellar feedback.

Star clusters are key environments for particle acceleration.

Superbubbles may significantly contribute to Galactic cosmic rays.

Abstract

Massive stars blow powerful winds and eventually explode as supernovae. By doing so, they inject energy and momentum in the circumstellar medium, which is pushed away from the star and piles up to form a dense and expanding shell of gas. The effect is larger when many massive stars are grouped together in bound clusters or associations. Large cavities form around clusters as a result of the stellar feedback on the ambient medium. They are called superbubbles and are characterised by the presence of turbulent and supersonic gas motions. This makes star clusters ideal environments for particle acceleration, and potential contributors to the observed Galactic cosmic ray intensity.