Evolution Of Supernova Remains In Environments With Density Gradients

Supernova remnants have extremely important value because they are probably the origin of the Galactic cosmic rays.The morphology of emission of supernova remnants depends sensitively on the initial conditions of the supernova ejecta and the surrounding medium,which leads to a variety of morphologies as indicated by multiband observation-s.At present,numerical simulation has become one of the important means to study the dynamic evolution and the emission morphology of supernova remnants.We investi-gate the dynamical evolution of supernova remnants through 3D HD simulation.Firstly,G349.7+00.2 is a young remnant with a mushroom morphology both in radio and in X-rays.It is interacting with a molecular cloud band on the observations in the radio and X-ray bands.Moreover,the remnant is interacting with a molecular cloud based on the observations in the radio and infrared band.When the ejecta has a mass of M_{e j}=8.0 M_⊙,a kinetic energy of E_ej=10⁵¹erg,a radius of R_ej=0.5pc,a density gradient of K=50cm^-3pc^-1,the number density of environmental media n₀=10cm^-3,polar angleθ=120°and azimuth angle?=250°,it can be concluded that the peculiar periphery of G349.7+00.2 and explain the obvious brightness enhancement along the southeast as the remnants interacting with the medium with a density gradient.Secondly,Multiband ob-servations of SNR0453-68.5 indicate that it has an approximately circular shape in radio,optical and X-ray bands.The reason for the formation of the periphery and the dynamical evolution of the remnant is investigated using 3D hydrodynamical（HD）simulations.Un-der the assumption that the supernova ejecta are evolved in the ambient medium with a density discontinuity,a density gradient and a uniform.When the simulation parameters are R_ej=1.0pc,K=5cm^-3pc^-1,n₀=0.42cm^-3,x=2.5,ξ=6,α=80°θ=200°,?=260°the main morphology features of the remains obtained in environmental media with a density discontinuity,a density gradient are consistent with that obtained by Chandra observation.