Deciphering the explosion mechanism of Type Ia SNe using their remnants II: a deep dive into double detonations with SNR 0509-67.5

Type Ia supernovae (SNe) occur when a white dwarf (WD) explodes via runaway thermonuclear burning. Till date, major uncertainties remain regarding the nature of the explosion mechanism and its observable signatures. In this work, we study how the double detonation explosion mechanism, or a helium shell detonation in a sub-Chandrasekhar WD followed by a core detonation, shapes supernova remnants (SNRs) and encodes information about the WD progenitor. We evolve a suite of double-detonation SN models to the remnant phase, up to several centuries after explosion, and measure the characteristic sizes of substructures formed in the SNR due to turbulent mixing. By comparing our models to high-resolution optical observations of the young Type Ia SNR 0509-67.5, we find that the size distribution of its small-scale substructures is consistent with a double detonation explosion mechanism and further places constraints on the carbon-oxygen core mass and helium shell mass of the WD progenitor. The observed sizes of iron-dominated and sulfur-dominated substructures in SNR 0509-67.5 indicate a progenitor core mass and a shell mass of 1 solar mass and greater than 0.05 solar mass, respectively.