Young Remnants of Type Ia Supernovae and Their Progenitors: A Study of SNR G1.9+0.3

TL;DR

This paper introduces a new diagnostic method called the Surface Brightness Index to distinguish between single and double degenerate progenitor scenarios of Type Ia supernovae, using observations of supernova remnant G1.9+0.3.

Contribution

It proposes a novel diagnostic tool and demonstrates its effectiveness in identifying the double degenerate progenitor for SNR G1.9+0.3, challenging previous assumptions.

Findings

Double degenerate progenitor explains flux rise and size increase

Single degenerate scenario is disfavored by observations

Circumstellar interaction can reveal progenitor types

Abstract

Type Ia supernovae, with their remarkably homogeneous light curves and spectra, have been used as standardizable candles to measure the accelerating expansion of the Universe. Yet, their progenitors remain elusive. Common explanations invoke a degenerate star (white dwarf) which explodes upon reaching close to the Chandrasekhar limit, by either steadily accreting mass from a companion star or violently merging with another degenerate star. We show that circumstellar interaction in young Galactic supernova remnants can be used to distinguish between these single and double degenerate progenitor scenarios. Here we propose a new diagnostic, the Surface Brightness Index, which can be computed from theory and compared with Chandra and VLA observations. We use this method to demonstrate that a double degenerate progenitor can explain the decades-long flux rise and size increase of the youngest known Galactic SNR G1.9+0.3. We disfavor a single degenerate scenario. We attribute the observed properties to the interaction between a steep ejecta profile and a constant density environment. We suggest using the upgraded VLA to detect circumstellar interaction in the remnants of historical Type Ia supernovae in the Local Group of galaxies. This may settle the long-standing debate over their progenitors.