Numerically investigating the peculiar periphery of a supernova remnant in the medium with a density gradient: the case of RCW 103

The young shell-type supernova remnant RCW 103 has peculiar properties in the X-ray morphology obtained with Chandra. The southeastern shell is more brighter in the X-rays, and the curved border of the shell in this region is more flatten than the other part. We investigate the formation of the peculiar periphery of the supernova remnant RCW 103 using 3D hydrodynamical simulation. Assuming that the supernova ejecta has been evolved in the medium with a density gradient, the detected shape of the periphery can be generally reproduced. For RCW 103, with the ejecta mass of $3.0~M_{\odot}$, the density of the background material of $2.0~\mathrm{cm}^{-3}$, and a gradient of $3.3 - 4.0 ~\mathrm{cm}^{-3} \mathrm{pc}^{-1}$, the X-ray periphery can be generally reproduced. The simulation turned out that the asymmetry of the SNR RCW 103 is mainly due to the inhomogeneous medium with a density gradient.