A Chandrasekhar Mass Progenitor for the Type Ia Supernova Remnant 3C 397 from The Enhanced Abundances of Nickel and Manganese

TL;DR

This study provides evidence that the Type Ia supernova remnant 3C 397 originated from a near-Chandrasekhar mass white dwarf, based on enhanced nickel and manganese abundances indicating neutronization in dense cores.

Contribution

It presents the first detection of strong K-shell emission from stable Fe-peak elements in 3C 397, supporting a single-degenerate progenitor scenario for this supernova remnant.

Findings

High Ni/Fe and Mn/Fe ratios indicate neutronization in the ejecta.

Evidence supports a Chandrasekhar mass progenitor for 3C 397.

Both single- and double-degenerate channels contribute to SN Ia rate.

Abstract

Despite decades of intense efforts, many fundamental aspects of Type Ia supernova (SNe Ia) remain elusive. One of the major open questions is whether the mass of the exploding white dwarf (WD) is close to the Chandrasekhar limit. Here we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11-0.24 and 0.018-0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the SN ejecta which can only be achieved by electron captures in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.