Supernovae in compact star clusters as sources of high-energy cosmic rays and neutrinos

Abstract

We discuss a specific population of galactic PeVatrons which may be the source of the galactic CR component well above PeV energies. Supernovae in compact clusters of massive stars are proposed as powerful sources of CRs, neutrinos, and gamma-ray emission. Numerical simulations of non-linear CR acceleration at converging shock flows have revealed that these accelerators can provide very hard spectra of protons up to 1016–1017eV which is well above the “knee” in the all-particle CR spectrum at about 3×1015eV. We suggest that known supernova remnants interacting with stellar winds in the compact clusters of young massive stars Westerlund I and Cl*1806-20 can be associated with the sources of the TeV gamma-emission detected by H.E.S.S. and may be responsible for a fraction of the high-energy neutrinos detected with the IceCube observatory. A recent cosmic ray (CR) composition measurement with the LOFAR array has revealed a light-mass component possibly dominating the all-particle spectrum at energies around 1017eV. Such a strong light component (mainly protons and helium) may require specific galactic CR sources such as supernovae interacting with compact clusters of massive stars in addition to isolated supernova remnants.