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The Origin of Cosmic Rays - A 96-Year-Old Puzzle Solved?

Arnon Dar
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Abstract

There is mounting evidence that long duration gamma ray bursts (GRBs) are produced by ultra-relativistic jets of ordinary matter which are ejected in core collapse supernova (SN) explosions. Such jets are extremely efficient cosmic ray (CR) accelerators which can accelerate the swept up ambient particles on their way to the highest observed CR energies. The bulk of the jet kinetic energy is used to accelerate CRs while only a tiny fraction is used to produce the GRB and its afterglow. Here we use the remarkably successful cannonball (CB) model of GRBs to show that the bipolar jets from SN explosions, which produce GRBs most of which are not beamed towards Earth, can be the main origin of cosmic rays at all energies. The model explains very simply the elemental composition of CRs and their observed spectra at all energies. In particular it explains the origin of the CR knees and ankle. Above the CR ankle, the Galactic magnetic fields can no longer delay the free escape of ultra-high energies CRs (UHECR) from the Galaxy, and the CRs from the intergalactic medium (IGM), which were injected there by SN jets from all the galaxies and isotropized there by the IGM magnetic fields, dominate the Galactic CR spectrum. A Greisen-Zatsepin-Kuzmin (GZK) effect due to the interaction of UHECRs with the microwave background radiation is expected. The CR nuclei which diffuse out of galaxies, or are directly deposited in the IGM by the relativistic SN jets, may be the origin of the IGM magnetic fields. Inverse Compton scattering of the cosmic microwave background radiation (MBR) by the CR electrons in the IGM produces the diffuse extragalactic gamma-ray background radiation (GBR).

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Arnon Dar. 2004-08-17. The Origin of Cosmic Rays - A 96-Year-Old Puzzle Solved?. https://doi.org/10.1393/ncb%2Fi2005-10119-y

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