Using fully kinetic simulations, we demonstrate that magnetic reconnection in relativistic plasmas is highly efficient at accelerating particles through a first-order Fermi process resulting from the curvature drift of particles in the direction of the electric field induced by the relativistic flows. This mechanism gives rise to the formation of hard power-law spectra in parameter regimes wher...

We revisit the high-energy spectral cutoff originating from the electron-positron pair creation in the prompt phase of gamma-ray bursts (GRBs) with numerical and analytical calculations. We show that the conventional exponential cutoff should be drastically modified to a steepened power-law in practical observations that integrate emissions from different internal shocks. Since the steepening i...

Weshow that the formation ofmagnetic field-aligned electric fields E‖ explains the existence of relativistic leptons with Lorentz factors less than about 2000 in active galactic nuclei. This Lorentz factor is the minimum value for Fermi processes to accelerate leptons. This is also known as the injection problem: particles with γ < 2000 cannot be accelerated by shock waves or MHD turbulence, al...

Processes driven by unsteady reconnection can efficiently accelerate particles in many astrophysical plasmas. An example is the jet fronts an outflow region. We present evidence of suprathermal ion acceleration between two consecutive observed Magnetospheric Multiscale mission terrestrial magnetotail. earthward propagating approached a second faster jet. Between jets, thermal ions are mostly pe...

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 accelerated during the process of structure formation, because of the supersonic motion of gas in the potential wells created by dark matter. At the shock waves that ...

1 Euratom/VR Fusion Association, Chalmers University of Technology, Gothenburg, S-41296,Sweden 2 Max-Planck-Institut für Plasmaphysik, EURATOM-IPP Association, Garching, Germany 3 Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Miusskaya 4, 125047 Moscow, Russia 4 Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP),Associat...

The usual Fermi processes are not efficient enough to account for the high energy cosmic ray acceleration in AGNs, Jet hot spots, GRBs, and in other compact object environments. It is proposed to accelerate particles by large perturbations in the relativistic plasmas of compact object environments where the Alfvén velocity is close to the velocity of light. Relativistic wavefronts are far more ...

The HESS collaboration recently reported the detection of TeV γ-ray emission coincident with Sgr A. In the context of other Galactic Center (GC) observations, this points to the following scenario: In the extreme advection-dominated accretion flow (ADAF) regime of the GC black hole (BH), synchrotron radio/sub-mm emission of ∼ 100MeV electrons emanates from an inefficiently radiating turbulent m...