Related papers: Reacceleration of electrons in supernova remnants
We discuss the generic characteristics of stochastic particle acceleration by a fully developed turbulence spectrum and show that resonant interactions of particles with high speed waves dominate the acceleration process. To produce the…
We study the stochastic electron acceleration by fast mode waves in the turbulent downstream of weakly magnetized collisionless astrophysical shocks. The acceleration is most efficient in a dissipative layer, and the model characteristics…
Recent gamma ray observations show that middle aged supernova remnants interacting with molecular clouds can be sources of both GeV and TeV emission. Models involving re-acceleration of pre-existing cosmic rays in the ambient medium and…
We study cosmic-ray acceleration in young Type Ia Supernova Remnants (SNRs) by means of test-particle diffusive shock acceleration theory and 1-D hydrodynamical simulations of their evolution. In addition to acceleration at the forward…
The presence of neutral hydrogen in the shock proximity changes the structure of the shock and affects the spectra of particles accelerated through the first-order Fermi mechanism. This phenomenon has profound implications for the…
In the leptonic scenario for TeV emission from a few well-observed shell-type TeV supernova remnants (STTSNRs), very weak magnetic fields are inferred. If fast-mode waves are produced efficiently in the shock downstream, we show that they…
Over the past decade, $\gamma$-ray observations of supernova remnants (SNRs) and accurate cosmic-ray (CR) spectral measurements have significantly advanced our understanding of particle acceleration in SNRs. In combination with…
Recent cosmic-ray measurements by the ATIC, CREAM and PAMELA experiments have found an apparent hardening of the energy spectrum at TeV energies. Although the origin of the hardening is not clearly understood, possible explanations include…
In the last few years several experiments have shown that the cosmic ray spectrum below the knee is not a perfect power-law. In particular, the proton and helium spectra show a spectral hardening by ~ 0.1-0.2 in spectral index at particle…
Recent cosmic-ray measurements have found an anomaly in the cosmic-ray energy spectrum at GeV-TeV energies. Although the origin of the anomaly is not clearly understood, suggested explanations include effect of cosmic-ray source spectrum,…
We simulate time-dependent particle acceleration in the blast wave of a young supernova remnant (SNR), using a Monte Carlo approach for the diffusion and acceleration of the particles, coupled to an MHD code. We calculate the distribution…
Shock waves associated with shell type supernova remnants are considered to be possible sites of cosmic ray acceleration. Since shocks are capable of accelerating electrons in addition to protons one anticipates both species to contribute…
The process that allows cosmic rays to escape from their sources and be released into the Galaxy is still largely unknown. The comparison between cosmic-ray electron and proton spectra measured at Earth suggests that electrons are released…
Here we investigate some aspects of stochastic acceleration of ultrarelativistic electrons by magnetic turbulence. In particular, we discuss the steady-state energy spectra of particles undergoing momentum diffusion due to resonant…
Recent observations of non-thermal X-rays from supernova remnants have been attributed to synchrotron radiation from the loss-steepened tail of a non-thermal distribution of electrons accelerated at the remnant blast wave. In diffusive…
Using a semi-analytic model of non-linear diffusive shock acceleration, we model the spectrum of cosmic ray (CR) electrons accelerated by supernova remnants (SNRs). Because electrons experience synchrotron losses in the amplified magnetic…
We present a 3-dimensional model of supernova remnants (SNRs) where the hydrodynamical evolution of the remnant is modeled consistently with nonlinear diffusive shock acceleration occuring at the outer blast wave. The model includes…
Plerionic supernova remnants exhibit radio emission with remarkably flat spectral indices ranging from $\alpha=0.0$ to $\alpha=-0.3$. The origin of very hard particle energy distributions still awaits an explanation, since shock waves…
The momentum distribution of particles accelerated at strong non-relativistic shocks may be influenced by the spatial distribution of the flow speed around the shock. This phenomenon becomes evident in the cosmic-ray modified shock, where…
Low frequency observations at 330 and 74 MHz can provide new insights into supernova remnants (SNR). We can test theoretical predictions for spectral index variations. Nonlinear models of shock acceleration predict that the spectra from…