2020/09/14 by Matteo Pais, Christoph Pfrommer
Physics and Astronomy · #Acceleration #Astrophysics #Astrophysics and Cosmic Phenomena #Computational physics #Cosmic ray #Galaxy #Gamma ray #Gamma-ray bursts and supernovae #Heliosphere #Interstellar medium #Magnetic field #Magnetohydrodynamics #Neutrino Physics Research #Particle acceleration #Physics #Pulsar #Solar wind #Supernova #Supernova remnant #Vela #astro-ph.HE
paper · pdf · doi:10.1093/mnras/staa2827
20 pages, 12 figures, accepted for publication on MNRAS
arxiv created 2020/09/14 · openalex publication_date 2020/09/16 · arxiv updated 2020/10/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT Supernova remnant (SNR) shocks provide favourable sites of cosmic ray (CR) proton acceleration if the local magnetic field direction is quasi-parallel to the shock normal. Using the moving-mesh magnetohydrodynamical (MHD) code arepo we present a suite of SNR simulations with CR acceleration in the Sedov–Taylor phase that combine different magnetic field topologies, density distributions with gradients and large-scale fluctuations, and – for our core-collapse SNRs – a multiphase interstellar medium with dense clumps with a contrast of 104. Assuming the hadronic gamma-ray emission model for the TeV gamma-ray emission, we find that large-amplitude density fluctuations of δρ/ρ0 ≳ 75 per cent are required to strongly modulate the gamma-ray emissivity in a straw man’s model in which the acceleration efficiency is independent of magnetic obliquity. However, this causes strong corrugations of the shock surface that are ruled out by gamma-ray observations. By contrast, magnetic obliquity-dependent acceleration can easily explain the observed variance in gamma-ray morphologies ranging from SN1006 (with a homogeneous magnetic field) to Vela Junior and RX J1713 (with a turbulent field) in a single model that derives from plasma particle-in-cell simulations. Our best-fitting model for SN1006 has a large-scale density gradient of ∇n ≃ 0.0034 cm−3 pc−1 pointing from south-west to north-east and a magnetic inclination with the plane of the sky of ≲10°. Our best-fitting model for Vela Junior and RX J1713 adopts a combination of turbulent magnetic field and dense clumps to explain their TeV gamma-ray morphologies and moderate shock corrugations.