Aspherical Remnants of Triple and Quadruple Detonations in Binary White Dwarfs

Abstract White dwarfs which explode by the double-detonation mechanism may have a binary white dwarf donor which is subsequently ignited by its collision with the ejecta. This results in the destruction of the donor via either the triple- or quadruple-detonation mechanism, adding significant mass to the resulting ejecta as well as modifying its structure and composition. We simulate the evolution of supernova remnants resulting from such detonations in a variety of binary progenitors and compare them against a double detonation with a surviving donor. Because of the time delay between the detonations of the two white dwarfs, high-velocity ejecta from the first explosion govern the first few centuries of remnant evolution, whereas at later times the dense core resulting from the donor detonation drives both the forward and reverse shocks to larger radii. The collision between the highest-velocity ejecta of the primary explosion and the donor carves a conical wake into the ejecta, which persists into the remnant phase regardless of whether or not the donor detonates. Our suite of simulated remnants is found to exhibit multiple distinguishing features of the explosion properties: a distinct X-ray morphology in the thermal emission and iron lines for triple detonations and smaller remnants with centrally concentrated emission for double detonations. The remnants are also varied in their elemental abundances and distributions, particularly for lighter elements, but these have limited observational utility and are sensitive to the properties of the progenitor binary.