%0 Journal Article
%T Massive stars as major factories of Galactic cosmic rays
%J -
%D 2019
%R https://doi.org/10.1038/s41550-019-0724-0
%X The identification of the main contributors to the locally observed fluxes of cosmic rays is a prime objective in the resolution of the long-standing enigma of the source of cosmic rays. We report on a compelling similarity of the energy and radial distributions of multi-TeV cosmic rays extracted from observations of very-high-energy ¦Ã-rays towards the Galactic Centre and two prominent clusters of young massive stars, Cygnus£¿OB2 and Westerlund£¿1. We interpret this resemblance as evidence that cosmic rays responsible for the diffuse very-high-energy ¦Ã-ray emission from the Galactic Centre are accelerated by the ultracompact stellar clusters located in the heart of the Galactic Centre. The derived 1/r decrement of the cosmic ray density with the distance from a star cluster is a distinct signature of continuous cosmic ray injection into the interstellar medium over a few million years. The lack of brightening of the ¦Ã-ray images towards the stellar clusters excludes the leptonic origin of ¦Ã-ray radiation. The hard, ¡ØE£¿2.3-type, power-law energy spectra of parent protons continues up to ~1£¿PeV. The efficiency of conversion of the kinetic energy of stellar winds to cosmic rays can be as high as 10%, implying that young massive stars may operate as proton PeVatrons with a dominant contribution to the flux of the highest-energy Galactic cosmic rays
%U https://www.nature.com/articles/s41550-019-0724-0