A Hydro-Based MCMC Analysis of SNR 0509-67.5 Revealing the Explosion Properties from Fluid Discontinuities Alone

Abstract

Using HST narrow-band Hα images of supernova remnant 0509-67.5 taken {\sim}10 years apart, we measure the forward shock (FS) proper motions (PMs) at 231 rim locations. The average shock radius and velocity are 3.66 {\pm} 0.036 pc and 6315 {\pm} 310 km s{^{-1}}. Hydrodynamic simulations, recast as similarity solutions, provide models for the remnant's expansion into a uniform ambient medium. These are coupled to a Markov chain Monte Carlo (MCMC) analysis to determine explosion parameters, constrained by the FS measurements. For specific global parameters, the MCMC posterior distributions yield an age of 315.5 {\pm} 1.8 yr, a dynamical explosion center at 5h09m31s.16s -67{^\circ}31{^\prime}17.1{^{\prime\prime}} and ambient medium densities at each azimuth ranging from 3.7-8.0 {\times} 10{^{-25}} g cm{^{-3}}. We can detect stellar PMs corresponding to speeds in the LMC of 770 km s{^{-1}} or more using the H$α$ images. Five stars in the remnant show measurable PMs but none appear to be moving radially from the center, including a prominent red star 4.6{^{\prime\prime}} from the center. Using coronal [Fe XIV] λ5303 emission as a proxy for the reverse shock location, we constrain the explosion energy (for a compression factor of 4) to a value of E = (1.30 {\pm} 0.41) {\times} 10{^{51}} erg for the first time from shock kinematics alone. Higher compression factors (7 or more) are strongly disfavored based on multiple criteria, arguing for inefficient particle acceleration in the Balmer shocks of 0509-67.5.