Relativistically Compressed Exploding White Dwarf Model for Sagittarius A East

Abstract

Recently, a new mechanism for Type I supernovae has been proposed whereby relativistic terms enhance the self-gravity of a carbon-oxygen white dwarf as it passes near a black hole. It was suggested that this relativistic compression can cause the central density to exceed the threshold for pycnonuclear reactions so that a thermonuclear runaway ensues. Here, we present numerical studies of such relativistically induced explosions of white dwarfs and red giant cores of various mass (particularly a typical 0.6 M☉ white dwarf) as they pass near a 3.7 × 106 M☉ black hole like Sgr A* in the Galactic center. We confirm by hydrodynamic thermonuclear burn simulations in three spatial dimensions that white dwarfs and red giant cores do indeed ignite and explode. In fact, they seem to explode even farther from the black hole than earlier estimates due to increased internal temperatures from adiabatic heating as the stars are compressed. We find that the compression is sufficiently fast that young white dwarfs can even be heated to thermonuclear rather than pycnonuclear ignition. We propose that such an event might explain the observed mixed-morphology Sgr A East supernova remnant in the Galactic center.