Wolf-Rayet stars in young massive star clusters as potential sources of Galactic cosmic rays

Abstract

For most elements, the isotopic ratios seen in cosmic rays (CRs) are similar to those in the solar wind. The most important exception to this is ${}^{22}$Ne/${}^{20}$Ne where the CR value is $\sim 5$ times that of the solar wind. According to most recent models of nucleosynthesis, a large amount of ${}^{22}\mathrm{Ne}$ is generated in Wolf-Rayet (WR) stars. In the winds of carbon sequence WR stars, i.e., WC stars, the isotopic ratio ${}^{22}\mathrm{Ne}$/${}^{20}\mathrm{Ne}$ can be much larger than in the solar wind. Here, we consider CRs produced by ${}^{22}\mathrm{Ne}$-enriched WR winds in compact clusters of young massive stars like Westerlund~1. We assume that efficient CR acceleration in clusters occurs over the WR lifetime in an ensemble of shock waves from multiple massive star winds. We estimate the fraction of all Galactic CRs such sources may produce for a given set of parameters.

arXiv comment5 pages, 1 figure, accepted for publication in IOP Journal of Physics: Conf. Series

References in corpus (15)

• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• Young massive star clusters
• Grids of stellar models with rotation II. WR populations and supernovae/GRB progenitors at Z = 0.014
• Galactic Cosmic Rays from Supernova Remnants: II Shock Acceleration of Gas and Dust
• On the mass function of star clusters
• Galactic Cosmic Rays from Supernova Remnants (I) - a Cosmic Ray Composition controlled by Volatility and Mass-to-Charge Ratio
• Cosmic ray neon, Wolf-Rayet stars, and the superbubble origin of galactic cosmic rays
• Nonthermal particles and photons in starburst regions and superbubbles
• The Unusual Initial Mass Function of the Arches Cluster
• On the shape of the spectrum of cosmic-rays accelerated inside superbubbles
• Not all stars form in clusters - measuring the kinematics of OB associations with $Gaia$
• The Starburst Cluster Westerlund 1: The Initial Mass Function and Mass Segregation
• Ultrahard spectra of PeV neutrinos from supernovae in compact star clusters
• On the origin and composition of Galactic cosmic rays
• Cosmic rays from supernova remnants and superbubbles

Cited by in corpus (2)

• Cosmic ray production in superbubbles
• Modeling of GeV-TeV gamma-ray emission of Cygnus Cocoon