Cosmic ray acceleration in magnetic circumstellar bubbles

TL;DR

This paper investigates how cosmic rays can be accelerated to energies beyond the 'knee' in the spectrum within magnetized bubbles formed by stellar winds, highlighting a potential source of high-energy cosmic rays.

Contribution

It demonstrates that interstellar bubbles created by stellar winds can facilitate cosmic ray acceleration to energies exceeding the 'knee', a novel environment for such processes.

Findings

Maximum particle energy can surpass the 'knee' in the spectrum.

Magnetized low-density gas in bubbles enables efficient acceleration.

Stellar wind bubbles are potential sources of high-energy cosmic rays.

Abstract

We consider the diffusive shock acceleration in interstellar bubbles created by powerful stellar winds of supernova progenitors. Under the moderate stellar wind magnetization the bubbles are filled by the strongly magnetized low density gas. It is shown that the maximum energy of particles accelerated in this environment can exceed the "knee" energy in the observable cosmic ray spectrum.