Turbulently-Driven Detonation Initiation in Electron-Degenerate Matter With Helium

Gabriel Casabona, Northwestern University

Photo of Gabriel Casabona

Type Ia supernovae (SNe Ia) are standardizable cosmological candles which led to the discovery of the accelerating universe. However, the physics of how white dwarfs (WDs) explode and lead to SNe Ia is still poorly understood. The initiation of the detonation front which rapidly disrupts the WD is a crucial element of the puzzle, and global 3D simulations of SNe Ia cannot resolve the length scales crucial to detonation initiation. In this work, we have performed local 3D hydrodynamical simulations of strongly-driven turbulence within electron-degenerate WD matter consisting of different ratios of helium, carbon, and oxygen. We demonstrate a novel pathway for detonation, in which strong turbulent dissipation rapidly heats the helium, and forms carbon and oxygen nuclei sufficient to lead to a detonation through accelerated burning via α captures. Simulations of strongly turbulent (RMS velocity of 103 km s-1 on 100 km scale) conditions lead to detonations in nearly all simulations considered here, even for initially pure helium with a mean density of 106 g cm-3.

Abstract Author(s): Gabriel Casabona, Robert T. Fisher