ASTRO-H White Paper - White Dwarf

TL;DR

This paper discusses the potential of ASTRO-H to study white dwarf binaries, focusing on their X-ray emissions, accretion physics, and the possibility of identifying progenitors of Type Ia supernovae through spectral analysis.

Contribution

It highlights how ASTRO-H's spectral resolution can advance understanding of white dwarf binaries and their role in supernova progenitors and Galactic X-ray emission.

Findings

Spectral resolution enables dynamical studies of X-ray plasma.

Potential to identify supernova progenitors via gravitational redshift.

Insights into accretion physics and high-density plasma behavior.

Abstract

Interacting binaries in which a white dwarf accretes material from a companion --- cataclysmic variables (CVs) in which the mass loss is via Roche-lobe overflow, and symbiotic stars in which the white dwarf captures the wind of a late type giant --- are relatively commonplace. They display a wide range of behaviors in the optical, X-rays, and other wavelengths, which still often baffles observers and theorists alike. They are likely to be a significant contributor to the Galactic ridge X-ray emission, and the possibility that some CVs or symbiotic stars may be the progenitors of some of the Type Ia supernovae deserves serious consideration. Furthermore, these binaries serve as excellent laboratories in which to study physics of X-ray emission from high density plasma, accretion physics, reflection, and particle acceleration. ASTRO-H is well-matched to the study of X-ray emission from many of these objects. In particular, the excellent spectral resolution of the SXS will enable dynamical studies of the X-ray emitting plasma. We also discuss the possibility of identifying an accreting, near-Chandrasekhar-mass white dwarf by measuring the gravitational redshift of the 6.4 keV line.