Most matter in the Universe consists of plasmas interspersed within magnetic fields, affecting the transport of charged particles known as cosmic rays (CRs). Despite extensive research, the origins and mechanisms driving CRs, especially the most energetic ones, remain elusive and at best partially understood. Anisotropic plasmas can emerge in astrophysical environments at cosmic outflows and shocks, such as supernova remnants, gamma-ray bursts, pulsars, and the jets of active galactic nuclei - all potential CR accelerators. Understanding how kinetic energy within relativistic outflows is converted into high-energy charged and neutral particles is a key focus of plasma astrophysics. Plasma instabilities, like the filamentation instability, can induce magnetic fields pivotal for jet formation and CR acceleration. Furthermore, CRs alter their paths while diffusing through interstellar magnetic fields, and they can amplify magnetic fields through induced instabilities.
Electron-positron pair beams, initiated by photon-photon interaction, can drive instabilities that influence electromagnetic cascades induced by high energy gamma-ray sources such as TeV blazars. With their relativistic jets pointing nearly towards the Earth, the blazar’s emission can probe the Universe over large scales, ranging from the diffuse extragalactic background light to the strength of intergalactic magnetic fields. Observing high-energy photons and neutrinos from distant sources helps unveil CR origins, bypassing magnetic deflection.

This Research Topic is dedicated to a special thematic collection of manuscripts aiming to delve into the intricacies of CR acceleration and transport with a focus on high-energy astrophysical multi-messenger sources. How to articulate the microphysics of CR-driven turbulence and magnetic field generation to such sources is an open issue. This interdisciplinary research topic at the intersection of High-Energy and Astroparticle Physics, Plasma Physics, Space Physics and Astronomy is open for contributions that cover, but are not limited to, the following themes:

• Astrophysical plasmas
• Plasma astrophysics in the lab
• Plasma instabilities
• Pair-beam instabilities and electromagnetic cascades from TeV blazars
• Large-scale cosmic magnetic fields
• Cosmic-ray induced magnetogenesis
• Cosmic-ray acceleration in astrophysical extreme environments
• Cosmic-ray propagation in turbulent magnetized environments
• Theoretical models and numerical simulations
• Multi-messenger astrophysical observations.

Are you interested in contributing a manuscript to this Research Topic?

The Role of Plasmas and Cosmic Magnetism in High-energy Astroparticle Physics