Simulation of the growth of the 3D Rayleigh-Taylor instability in Supernova Remnants using an expanding reference frame

TL;DR

This paper uses hydrodynamic simulations with an expanding reference frame to study how Rayleigh-Taylor instabilities develop in supernova remnants, considering effects like particle acceleration and cosmic rays.

Contribution

It introduces a super-comoving coordinate system in simulations to accurately model Rayleigh-Taylor growth and explores the impact of particle acceleration on remnant morphology.

Findings

Rayleigh-Taylor structures are slightly affected by cosmic ray dominance.

Ejecta penetration into the interstellar medium is reduced with cosmic ray acceleration.

Reverse shock perturbations increase when acceleration occurs at both shocks.

Abstract

Context: The Rayleigh-Taylor instabilities generated by the deceleration of a supernova remnant during the ejecta-dominated phase are known to produce finger-like structures in the matter distribution which modify the geometry of the remnant. The morphology of supernova remnants is also expected to be modified when efficient particle acceleration occurs at their shocks. Aims: The impact of the Rayleigh-Taylor instabilities from the ejecta-dominated to the Sedov-Taylor phase is investigated over one octant of the supernova remnant. We also study the effect of efficient particle acceleration at the forward shock on the growth of the Rayleigh-Taylor instabilities. Methods: We modified the Adaptive Mesh Refinement code RAMSES to study with hydrodynamic numerical simulations the evolution of supernova remnants in the framework of an expanding reference frame. The adiabatic index of a relativistic gas between the forward shock and the contact discontinuity mimics the presence of accelerated particles. Results: The great advantage of the super-comoving coordinate system adopted here is that it minimizes numerical diffusion at the contact discontinuity, since it is stationary with respect to the grid. We propose an accurate expression for the growth of the Rayleigh-Taylor structures that connects smoothly the early growth to the asymptotic self-similar behaviour. Conclusions: The development of the Rayleigh-Taylor structures is affected, although not drastically, if the blast wave is dominated by cosmic rays. The amount of ejecta that makes it into the shocked interstellar medium is smaller in the latter case. If acceleration occurs at both shocks the extent of the Rayleigh-Taylor structures is similar but the reverse shock is strongly perturbed.