Simulating TeV gamma-ray morphologies of shell-type supernova remnants

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 magneto-hydrodynamical (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 multi-phase interstellar medium with dense clumps with a contrast of $10^4$. Assuming the hadronic gamma-ray emission model for the TeV gamma-ray emission, we find that large-amplitude density fluctuations of $\delta \rho /{\rho }_0\gtrsim 75$ 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-fit model for SN1006 has a large-scale density gradient of $\nabla n\simeq 0.0034{\mathrm{cm}}^{-3}{\mathrm{pc}}^{-1}$ pointing from south-west to north-east and a magnetic inclination with the plane of the sky of $\lesssim 10^{\circ }$. Our best-fit 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.

20 pages, 12 figures, accepted for publication on MNRAS

References in corpus (22)

• Draping of Cluster Magnetic Fields over Bullets and Bubbles -- Morphology and Dynamic Effects
• Observations of the young supernova remnant RX J1713.7-3946 with the Fermi Large Area Telescope
• Observational constraints on energetic particle diffusion in young SNRs: amplified magnetic field and maximum energy
• First detection of VHE gamma-rays from SN 1006 by H.E.S.S
• Simulating cosmic rays in clusters of galaxies - II. A unified scheme for radio halos and relics with predictions of the gamma-ray emission
• Simulations and Theory of Ion Injection at Non-relativistic Collisionless Shocks
• Study of Nonthermal Emission from SNR RX J1713.7-3946 with Suzaku
• Confirmation of strong magnetic field amplification and nuclear cosmic ray acceleration in SN 1006
• Simulations of Ion Acceleration at Non-relativistic Shocks. III. Particle Diffusion
• Hadronic gamma-rays from RX J1713.7-3946?
• On the Expansion Rate, Age, and Distance of the Supernova Remnant G266.2-1.2 (Vela Jr.)
• The Slow X-Ray Expansion of the Northwestern Rim of the Supernova Remnant RX J0852.0-4622
• Shock finding on a moving-mesh: I. Shock statistics in non-radiative cosmological simulations
• The gas density around SN 1006
• A detailed study of the interstellar protons toward the TeV $\gamma$-ray SNR RX J0852.0$-$4622 (G266.2$-$1.2, Vela Jr.); a third case of the $\gamma$-rays and ISM spatial correspondence
• 3D MHD simulation of polarized emission in SN 1006
• Expansion measurement of Supernova Remnant RX J1713.7-3946
• Cosmic Ray Origins in Supernova Blast Waves
• Non-linear weak lensing forecasts
• Analysis of GeV-band gamma-ray emission from SNR RX J1713.7-3946
• Hydrodynamic simulations of the interaction of supernova shock waves with a clumpy environment: the case of the RX J0852.0-4622 (Vela Jr) supernova remnant
• Origin(s) of Cosmic Rays