The Origin of Galactic Cosmic Rays as Revealed by their Composition

Discussion timeslot (ZOOM-Meeting): 15. July 2021 - 18:00
ZOOM-Meeting URL: https://desy.zoom.us/j/98542982538
ZOOM-Meeting ID: 98542982538
ZOOM-Meeting Passcode: ICRC2021
Corresponding Session: https://icrc2021-venue.desy.de/channel/44-The-Origins-of-Galactic-Cosmic-Rays-GAD-GAI-CRD/125
Live-Stream URL: https://icrc2021-venue.desy.de/livestream/Discussion-04/5

Abstract:
'Galactic cosmic-rays (GCRs) are thought to be accelerated by the first order Fermi mechanism in strong shocks induced by massive star winds and supernova explosions sweeping across the interstellar medium (ISM). But the phase of the ISM from which the CRs are extracted has remained elusive up to now. Using the latest CR composition data from the AMS-02, Voyager-1 and SuperTIGER experiments, we show that the volatile elements of the CR material are mainly accelerated from a plasma of temperature of approximately 3 million Kelvin, which is typical of the hot and tenuous medium found in galactic superbubbles energized by the combined activities of massive star winds and core-collapse supernova explosions. In addition, we identify a CR component arising from acceleration of massive star winds in their termination shocks, which is responsible for the overabundance of 22-Ne in the GCR composition. The CR composition also shows evidence for a preferential acceleration of refractory elements contained in ISM dust. We suggest that this component arises from the acceleration of dust grains continuously injected into superbubbles through evaporation of adjacent molecular clouds. We derive the acceleration efficiencies for these various components and compare them to those predicted by the diffuse shock acceleration theory.'

Authors: Vincent Tatischeff
Co-Authors: John C. Raymond | Jean Duprat | Stefano Gabici | Sarah Recchia
Indico-ID: 241
Proceeding URL: https://pos.sissa.it/395/153