A CHANDRASEKHAR MASS PROGENITOR FOR THE TYPE Ia SUPERNOVA REMNANT 3C 397 FROM THE ENHANCED ABUNDANCES OF NICKEL AND MANGANESE

Abstract

Despite decades of intense efforts, many fundamental aspects of Type Ia\nsupernova (SNe Ia) remain elusive. One of the major open questions is whether\nthe mass of the exploding white dwarf (WD) is close to the Chandrasekhar limit.\nHere we report the detection of strong K-shell emission from stable Fe-peak\nelements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C\n397. The high Ni/Fe and Mn/Fe mass ratios (0.11-0.24 and 0.018-0.033,\nrespectively) in the hot plasma component that dominates the K-shell emission\nlines indicate a degree of neutronization in the SN ejecta which can only be\nachieved by electron captures in the dense cores of exploding WDs with a\nnear-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397,\nsince Chandrasekhar mass progenitors are expected naturally if the WD accretes\nmass slowly from a companion. Together with other results supporting the\ndouble-degenerate scenario, our work adds to the mounting evidence that both\nprogenitor channels make a significant contribution to the SN Ia rate in\nstar-forming galaxies.\n