Signature of the explosion mechanism of Type-Ia SNe in substructures of the remnant: the case of Tycho's SNR

TL;DR

This paper introduces a novel method to identify Type-Ia supernova explosion mechanisms by analyzing the sizes of turbulent substructures in supernova remnants, linking observable features to specific explosion models.

Contribution

The study presents a new approach using 3D hydrodynamical models to connect SNR substructure sizes with explosion mechanisms, applied successfully to Tycho's SNR.

Findings

Tycho's SNR structure aligns with a sub-Chandrasekhar mass WD explosion via double-detonation.

Substructure size differences are indicative of different explosion mechanisms.

The method can be extended to other SNRs to infer their explosion origins.

Abstract

Type-Ia supernovae (SNe), or runaway thermonuclear explosions of white dwarfs (WDs), play a critical role in the chemical evolution of galaxies, and are important cosmological distance indicators due to their 'standardizable' lightcurves. Growing evidence, however, suggests greater diversity in their observed lightcurves (and spectra) than thought previously. This is usually attributed to a variety of WD explosion mechanisms and progenitor system properties, but a direct link between the explosion mechanisms and Type-Ia SN observables remains elusive. Here we present a novel approach to identify explosion mechanisms of Type-Ia SNe, by analyzing the sizes of small-scale turbulent substructures of different elements in their extended ejecta, i.e., in Supernova Remnants (SNRs). Our three-dimensional hydrodynamical models show that substructures in an SNR dominated by iron-group elements may have a typical size different from substructures dominated by intermediate mass elements (e.g., Si, S) in the same SNR. This size difference is governed by the explosion mechanism. Applying this approach to Tycho's SNR, we find that its observed structure is most consistent with the explosion of a sub-Chandrasekhar mass WD via the double-detonation mechanism. Extending this method to other well-characterized SNRs can let us connect the inferred explosion mechanism to the associated historical SNe, which often have spectra reconstructed through light echo observations.