Related papers: Cosmic Ray Acceleration in Hydromagnetic Flux Tube…
When a magnetised, thermal plasma containing a shock wave efficiently accelerates Cosmic Rays (CR) a reaction is exerted on the fluid structure. The simplest description of this process involves three conservation equations for the…
Cosmic Ray (CR) acceleration still challenges the researchers. Fast particles may be accelerated in astrophysical environments by a variety of processes. Acceleration in magnetic reconnection sites in particular, has lately attracted the…
We analyse the transport of cosmic rays (CR) in magnetic fields that are structured on scales greater than the CR Larmor radius. We solve the Vlasov-Fokker-Planck (VFP) equation for various mixes of mirroring and small-angle scattering and…
We investigate a mechanism for accelerating cool (10$^4$ K) clouds in the circumgalactic medium (CGM) with cosmic rays (CRs), possibly explaining some characteristics of observed high velocity clouds (HVCs). Enforcing CRs to stream down…
Clusters of galaxies are storage rooms of cosmic rays. They confine the hadronic component of cosmic rays over cosmological time scales due to diffusion, and the electron component due to energy losses. Hadronic cosmic rays can be…
We derive the maximum accelerated particle energy from first-order and second-order Fermi acceleration at nonrelativistic and relativistic shocks for explosions taking place in a uniform surrounding medium. Second-order stochastic processes…
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…
A review of theoretical results on cosmic ray first-order Fermi acceleration at relativistic shock waves is presented, with recent results substantially changing the existing knowledge on these processes. In particular one can not expect…
Theory of the first-order Fermi acceleration of cosmic ray particles at relativistic shock waves is reviewed. We consider shocks with parallel and oblique, sub- and super-luminal magnetic field configurations and with finite-amplitude…
Turbulence is ubiquitous in astrophysics. It radically changes many astrophysical phenomena, in particular, the propagation and acceleration of cosmic rays. We present the modern understanding of compressible magnetohydrodynamic (MHD)…
We consider the acceleration of charged particles at the ultra-relativistic shocks, with Lorentz factors \Gamma_s >> 1 relative to the upstream medium, arising in relativistic fireball models of gamma-ray bursts (GRBs). We show that for…
The {\it Fermi} Large Area Telescope has recently discovered two giant gamma-ray bubbles which extend north and south of the Galactic center with diameters and heights of the order of $H\sim 10$ kpc. We suggest that the periodic star…
The dynamic processes of magnetic reconnection and turbulence cause magnetic islands/flux-ropes generation. The in-situ observations suggest that the coalescence or/and contraction of magnetic islands are responsible to the charged particle…
We shortly discuss several astrophysical scenarios leading to cosmic ray acceleration up to extremely high energies reaching the scale of 10^{20} eV. The processes suggested in the literature include acceleration at relativistic jet…
If gamma-ray bursts are sources of ultra-high energy cosmic rays, then radiative signatures of hadronic acceleration are expected in GRB data. Observations with the Fermi Gamma-ray Space Telescope offer the best means to search for evidence…
The acceleration of ultra high energy cosmic rays is conjectured to occur through various interactions with the electromagnetic fields in different astrophysical objects, like magnetic matter clumps, besides the well-known shock and…
Diffusion of cosmic rays (CRs) is the key process of understanding their propagation and acceleration. We employ the description of spatial separation of magnetic field lines in MHD turbulence in Lazarian & Vishniac (1999) to quantify the…
In a weakly compressible high-$\beta$ medium, pitch-angle scattering and the associated scattering acceleration of cosmic rays (CRs) by anisotropic Alfv\'{e}n and slow modes of magnetohydrodynamic (MHD) turbulence is inefficient. To tap the…
Theoretical studies of cosmic ray particle acceleration in the first-order Fermi process at relativistic shocks are reviewed. At the beginning we discuss the acceleration processes acting at mildly relativistic shock waves. An essential…
We have calculated the cosmic ray (CR) acceleration at young remnants from Type Ia supernovae expanding into a uniform interstellar medium (ISM). Adopting quasi-parallel magnetic fields, gasdynamic equations and the diffusion convection…