2021/02/01 by Elena Amato, S. Casanova, Sabrina Casanova
Physics and Astronomy · #Acceleration #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Classical mechanics #Cosmic microwave background #Cosmic ray #Dark Matter and Cosmic Phenomena #Galaxy #Particle acceleration #Physics #Solar and Space Plasma Dynamics #astro-ph.HE #physics.plasm-ph
paper · pdf · doi:10.1017/s0022377821000064
published as Journal of Plasma Physics, Volume 87, Issue 1, article id.845870101, 2021
openalex publication_date 2021/02/01 · arxiv created 2021/04/26 · arxiv updated 2021/04/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Accelerated particles are ubiquitous in the Cosmos and play a fundamental role in many processes governing the evolution of the Universe at all scales, from the sub-AU scale relevant for the formation and evolution of stars and planets to the Mpc scale involved in Galaxy assembly. We reveal the presence of energetic particles in many classes of astrophysical sources thanks to their production of non-thermal radiation, and we detect them directly at the Earth as cosmic rays. In the last two decades both direct and indirect observations have provided us a wealth of new, high-quality data about cosmic rays and their interactions both in sources and during propagation, in the Galaxy and in the Solar System. Some of the new data have confirmed existing theories about particle acceleration and propagation and their interplay with the environment in which they occur. Some others have brought about interesting surprises, whose interpretation is not straightforward within the standard framework and may require a change of paradigm in terms of our ideas about the origin of cosmic rays of different species or in different energy ranges. In this article, we focus on cosmic rays of galactic origin, namely with energies below a few petaelectronvolts, where a steepening is observed in the spectrum of energetic particles detected at the Earth. We review the recent observational findings and the current status of the theory about the origin and propagation of galactic cosmic rays.