Origin and impacts of the first cosmic rays

Yutaka Ohira, Kohta Murase

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


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.

Original languageEnglish (US)
Article number061301
JournalPhysical Review D
Issue number6
StatePublished - Sep 17 2019

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)


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