Particle acceleration in interstellar shocks

Abstract

This review presents the fundamentals of the particle acceleration processes active in interstellar medium (ISM), which are essentially based on the so-called Fermi mechanism theory. More specifically, the review presents here in more details the first order Fermi acceleration process -also known as diffusive shock acceleration (DSA) mechanism. In this case, acceleration is induced by the interstellar (IS) shock waves. These IS shocks are mainly associated with emission nebulae (H ii regions, planetary nebulae and supernova remnants). Among all types of emission nebulae, the strongest shocks are associated with supernova remnants (SNRs). Due to this fact they also provide the most efficient manner to accelerate ISM particles to become high energy particles, i.e. cosmic-rays (CRs). The review therefore focuses on the particle acceleration at the strong shock waves of supernova remnants.

Non-linear diffusive shock acceleration: A recipe for injection of electrons

“…For modelling proton and electron spectra we shall use Blasi's semi-analytical model whose details can be found in [32,33] (see also [12,23,[34][35][36][37][38][39]). Blasi's model implies solving coupled equations (obtained from diffusion-advection equations and mass and momentum conservation):…”

Editorial: Plasma, particles, and photons: ISM physics revisited

“…In this topical collection we collect reviews and new results in ISM research with an emphasis on multi-messenger Astrophysics. There are contributions on the production of cosmic ray (CR) electrons (Alsaberi et al 2019) and their transport (Heesen 2021) as deduced from observations, the generation of X-rays and cosmic γ -rays in interstellar shocks (Sano and Fukui 2021), the mechanism of particle acceleration via diffuse shock acceleration (Urošević et al 2019), the thermal and non-thermal X-ray emission from superbubbles (Kavanagh 2020), and the characteristics of non-equilibrium ionisation plasmas (Breitschwerdt and de Avillez 2021). Next, there are contributions on simulations of cosmic ray propagation (Mertsch 2020), on their detection (Albrecht et al 2022) and what we can learn from that, on interstellar radioactive isotopes (Diehl 2021), and on observations of neutrinos (Kheirandish 2020).…”

“…For interstellar shock waves to arise, ionisation in the medium is required, and the acceleration of particles in the shocks and the amplification of magnetic fields in the interstellar plasma are strongly coupled (Breitschwerdt and de Avillez 2021). In the strong shock waves of stellar winds and supernovae, particles are accelerated to very high energies (Urošević et al 2019) which then diffuse through interstellar space and are observed on Earth as cosmic rays. The shock waves will also encounter inhomogeneities in the interstellar medium.…”

Probing the particle acceleration at trans-relativistic shocks with gamma-ray burst afterglows

“…Particle acceleration across collisionless shock waves, called diffusive shock acceleration or first-order Fermi acceleration, is thought to be a mechanism to produce non-thermal high-energy particles in astrophysical phenomena (Drury 1983;Blandford & Eichler 1987;Axford 1994;Sironi et al 2015;Urošević et al 2019;Marcowith et al 2020, for reviews). While the details of the acceleration mechanism are still under debate, particle acceleration appears to work both in relativistic and non-relativistic shocks as indicated by observations of gamma-ray bursts (GRBs) and supernova remnants (SNRs).…”