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Molecular clouds are known to be clumpy, with dense molecular clumps occupying only a few percent of the volume. A supernova remnant then evolves primarily in the interclump medium, and becomes radiative at a radius of about 6 pc, forming a…

Astrophysics · Physics 2009-10-30 Roger A. Chevalier

Supernova remnants (SNRs) are often considered as the main sites of acceleration of cosmic rays in our Galaxy, possibly up to the knee. However, their ability to accelerate particles to reach PeV energies is questionable and lacks…

High Energy Astrophysical Phenomena · Physics 2025-08-06 Iurii Sushch , Pasquale Blasi , Robert Brose

The theory of diffusive particle acceleration explains the spectral properties of the cosmic rays below energies of approx. 10^6 GeV as produced at strong shocks in supernova remnants (SNR's). To supply the observed flux of cosmic rays, a…

Astrophysics · Physics 2007-05-23 U. D. J. Gieseler , T. W. Jones , Hyesung Kang

We describe a semi-analytical approach to non-linear diffusive shock acceleration in the case in which nuclei other than protons are also accelerated. The structure of the shock is determined by the complex interplay of all nuclei, and in…

High Energy Astrophysical Phenomena · Physics 2010-11-10 D. Caprioli , P. Blasi , E. Amato

Supernova Remnants (SNRs) are believed to be the main source of Galactic cosmic rays (CR). The strong SNR shocks provide ideal acceleration sites for particles of at least 10^14 eV/nucleon. Radio continuum studies of SNRs carried out with…

High Energy Astrophysical Phenomena · Physics 2011-11-08 G. Dubner

Recent precise measurements of cosmic ray (CR) spectra show that the energy distribution of protons is softer than those of heavier nuclei, and there are spectral hardenings for all nuclear compositions above $\sim$200 GV. Models proposed…

High Energy Astrophysical Phenomena · Physics 2017-08-02 Yiran Zhang , Siming Liu , Qiang Yuan

The proof of cosmic ray (CR) origin in supernova remnants (SNR) must hinge on full consistency of the CR acceleration theory with the observations; direct proof is impossible because of the orbit stochasticity of CR particles. Recent…

Astrophysics of Galaxies · Physics 2016-10-11 M. A. Malkov , P. H. Diamond , R. Z. Sagdeev

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…

Astrophysics · Physics 2009-11-10 S. P. Reynolds

We compute the spectra of cosmic-ray (CR) nuclei and antinuclei under a scenario where hadronic interaction processes inside supernova remnants (SNRs) can produce a diffusively-shock-accelerated "source component" of secondary particles.…

High Energy Astrophysical Phenomena · Physics 2018-07-31 Nicola Tomassetti , Alberto Oliva

The giant molecular clouds (MCs) found in the Milky Way and similar galaxies play a crucial role in the evolution of these systems. The supernova explosions that mark the death of massive stars in these regions often lead to interactions…

High Energy Astrophysical Phenomena · Physics 2015-06-22 P. Slane , A. Bykov , D. C. Ellison , G. Dubner , D. Castro

Supernova remnants (SNRs) are believed to accelerate particles up to high energies through the mechanism of diffusive shock acceleration (DSA). Except for direct plasma simulations, all modeling efforts must rely on a given form of the…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Gilles Ferrand , Rebecca J. Danos , Andreas Shalchi , Samar Safi-Harb , Paul Edmon , Peter Mendygral

Nonlinear model of diffusive shock acceleration is used for investigation of the particle acceleration in old supernova remnants W28 and W44. We modeled the hydrodynamical evolution of the remnants, shock modification and streaming…

High Energy Astrophysical Phenomena · Physics 2017-01-17 V. N. Zirakashvili , V. S. Ptuskin

We outline the main features of nuclei acceleration at supernova remnant forward shocks, stressing the crucial role played by self-amplified magnetic fields in determining the energy spectrum observed in this class of sources. In…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Damiano Caprioli

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…

Astrophysics · Physics 2011-05-23 A. Mastichiadis

We performed kinetic simulations of diffusive shock acceleration in Type Ia supernova remnants (SNRs) expanding into a uniform interstellar medium (ISM). The preshock gas temperature is the primary parameter that governs the cosmic ray (CR)…

High Energy Astrophysical Phenomena · Physics 2011-05-20 Hyesung Kang

The spectra of high-energy protons and nuclei accelerated by supernova remnant shocks are calculated taking into account magnetic field amplification and Alfvenic drift both upstream and downstream of the shock for different types of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 V. S. Ptuskin , V. N. Zirakashvili , E. S. Seo

We discuss the acceleration and escape of secondary cosmic-ray (CR) nuclei, such as lithium, beryllium and boron, produced by spallation of primary CR nuclei like carbon, nitrogen, and oxygen accelerated at the shock in supernova remnants…

High Energy Astrophysical Phenomena · Physics 2021-08-25 Norita Kawanaka , Shiu-Hang Lee

Supernova remnants (SNRs) have been regarded for many decades as the sources of Galactic cosmic rays (CRs) up to a few PeV. However, only with the advent of Fermi-LAT it has been possible to detect - at least in some SNRs - \gamma-rays…

High Energy Astrophysical Phenomena · Physics 2013-03-12 Damiano Caprioli

Particle acceleration occurs on a range of scales from AU in the heliosphere to Mpc in clusters of galaxies and to energies ranging from MeV to EeV. A number of acceleration processes have been proposed, but diffusive shock acceleration…

High Energy Astrophysical Phenomena · Physics 2014-05-08 A R Bell

Recent observations of the supernova remnant W44 by the \emph{Fermi} spacecraft observatory strongly support the idea that the bulk of galactic cosmic rays is accelerated in such remnants by a Fermi mechanism, also known as diffusive shock…

High Energy Astrophysical Phenomena · Physics 2011-03-04 M. A. Malkov , P. H. Diamond , R. Z. Sagdeev