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 22Ne/20Ne where the CR value is ∼ 5 times that of the solar wind. According to most recent models of nucleosynthesis, a large amount of 22Ne is generated in Wolf-Rayet (WR) stars. In the winds of carbon sequence of WR stars, i.e., WC stars, the isotopic ratio 22Ne/20Ne can be much larger than in the solar wind. Here, we consider CRs produced by 22Ne-enriched WR winds in young massive star clusters assuming the acceleration occurs from an ensemble of shock waves from the massive stars' winds. We estimate the fraction of all Galactic CRs such sources may produce for a given set of parameters.