Related papers: Constraints on Particle Acceleration from the Diff…
Theoretical concepts ofn cosmic ray particle acceleration at relativistic plasma flows -- shocks and shear layers -- are reviewed. We begin with a discussion of mildly relativistic shock waves. The role of oblique field configurations and…
The cosmic ray energy spectra of protons and helium nuclei, which are the most abundant components of cosmic radiation, exhibit a remarkable hardening at energies above one hundred GeV/nucleon. Recent data from AMS-02 confirms this feature…
A cosmic acceleration mechanism is introduced which is based on the wakefields excited by the Alfven shocks in a relativistically flowing plasma, where the energy gain per distance of a test particle is Lorentz invariant. We show that there…
The ultra-high energy cosmic rays observed at the Earth are most likely accelerated in extra-galactic sources. For the typical luminosities invoked for such sources, the electric current associated to the flux of cosmic rays that leave them…
Shocks of supernova remnants (SNRs) accelerate charged particles up to 100 TeV range via diffusive shock acceleration (DSA) mechanism. It is believed that shocks of SNRs are the main contributors to the pool of Galactic cosmic rays,…
Particle acceleration in the dynamically evolving environment of Supernova Remnants is discussed in the framework of a genuinely time-dependent nonlinear theory, assuming spherical symmetry. As a consequence the dependence of injection on…
Radiation pressure acceleration (RPA) is a highly efficient mechanism of laser-driven ion acceleration, with with near complete transfer of the laser energy to the ions in the relativistic regime. However, there is a fundamental limit on…
Ultra-high energy cosmic ray protons accelerated in astrophysical objects produce secondary electromagnetic cascades during propagation in the cosmic microwave and infrared backgrounds. We show that such cascades can contribute between ~1%…
The hunt for cosmic TeV particle accelerators is prospering through Imaging Atmospheric Cerenkov Telescopes. We face challenges such as low light levels and MHz trigger rates, and the need to distinguish between particle air showers…
Diffuse emission from the Milky Way dominates the gamma-ray sky. About 80% of the high-energy luminosity of the Milky Way comes from processes in the interstellar medium. The Galactic diffuse emission traces interactions of energetic…
The existence and extent of non-thermal phenomena in galaxy clusters is now well established. A key question in our understanding of these phenomena is the origin of the relativistic electrons which may be constrained by the modelling of…
Possible entropy constraints on particle acceleration spectra are discussed. Solar flare models invoke a variety of initial distributions of the primary energy release over the particles of the flare plasma -- ie., the partition of the…
Gamma ray emission lines resulting from accelerated particle bombardment of ambient gas can serve as an important spectroscopic tool for abundance determinations. The method is illustrated by considering the gamma ray line emission observed…
Context: Typical space plasmas contain spatially and temporally variable turbulent electromagnetic fields. Understanding the transport of energetic particles and the acceleration mechanisms for charged particles is an important goal of…
The acceleration of the expansion of the universe has been argued for by several research groups. If the universe is accelerating and if the universe or some part of the universe has a charge, then there may be electromagnetic radiation…
If cosmic ray protons interact with gas at roughly the mean density of the interstellar medium in starburst galaxies, then pion decay in starbursts is likely to contribute significantly to the diffuse extra-galactic background in both…
(abridged abstract) Theoretical arguments indicate that close-in terrestial exoplanets may have weak magnetic fields, especially in the case of planets more massive than Earth (super-Earths). Planetary magnetic fields, however, constitute…
Relativistic sources, e.g. gamma-ray bursts, pulsar wind nebulae and powerful active galactic nuclei produce relativistic outflows that lead to the formation of collisionless shock waves, where particle acceleration is thought to take…
The propagation of very high energy gamma-rays ($E>100$~GeV) over cosmological distances is suppressed by pair-production processes with the ubiquitous extra-galactic soft photon background, mainly in the optical to near infra-red. The…
High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The six or more pulsars seen by CGRO/EGRET show that: the light curves usually have double-peak…