Origin and impacts of the first cosmic rays

Nonthermal phenomena are ubiquitous in the Universe, and cosmic rays (CRs) play various roles in different environments. When, where, and how are CRs first generated since the big bang? We argue that blast waves from the first cosmic explosions at z∼20 lead to Weibel mediated nonrelativistic shocks...

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Bibliographic Details
Published in:Physical review. D 2019-09, Vol.100 (6), Article 061301
Main Authors: Ohira, Yutaka, Murase, Kohta
Format: Article
Language:English
Subjects:
Acceleration
Accelerators
Big bang cosmology
Cosmic rays
Deposition
Ejecta
Explosions
Galactic evolution
Gamma rays
Star & galaxy formation
Universe
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Summary:Nonthermal phenomena are ubiquitous in the Universe, and cosmic rays (CRs) play various roles in different environments. When, where, and how are CRs first generated since the big bang? We argue that blast waves from the first cosmic explosions at z∼20 lead to Weibel mediated nonrelativistic shocks and CRs can be generated by the diffusive shock acceleration mechanism. We show that protons are accelerated at least up to sub-GeV energies, and the fast velocity component of supernova ejecta is likely to allow CRs to achieve a few GeV in energy. We discuss other possible accelerators of the first CRs, including accretion shocks due to the cosmological structure formation. These CRs can play various roles in the early Universe, such as the ionization and heating of gas, the generation of magnetic fields, and feedbacks on the galaxy formation.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.100.061301