Circumstellar absorption in double detonation Type Ia supernovae

TL;DR

This paper investigates how a hydrogen-rich layer on white dwarfs affects mass transfer in binary systems, leading to circumstellar material that matches observations of Type Ia supernovae, supporting the double detonation model.

Contribution

It demonstrates that the hydrogen-rich layer is stably transferred and ejected, creating circumstellar environments consistent with observed supernova absorption features, thus supporting the double detonation scenario.

Findings

Hydrogen-rich layer is ejected before supernova explosion.

Ejected material forms circumstellar medium matching observations.

Supports double detonation as a viable Type Ia supernova mechanism.

Abstract

Upon formation, degenerate He core white dwarfs are surrounded by a radiative H-rich layer primarily supported by ideal gas pressure. In this Letter, we examine the effect of this H-rich layer on mass transfer in He+C/O double white dwarf binaries that will eventually merge and possibly yield a Type Ia supernova (SN Ia) in the double detonation scenario. Because its thermal profile and equation of state differ from the underlying He core, the H-rich layer is transferred stably onto the C/O white dwarf prior to the He core's tidal disruption. We find that this material is ejected from the binary system and sweeps up the surrounding interstellar medium hundreds to thousands of years before the SN Ia. The close match between the resulting circumstellar medium profiles and values inferred from recent observations of circumstellar absorption in SNe Ia gives further credence to the resurgent double detonation scenario.