A Cr-K emission line survey in young supernova remnants with Chandra

TL;DR

This study surveys Cr-K emission lines in young supernova remnants using Chandra data, confirming and discovering lines across multiple remnants, and explores their implications for nucleosynthesis and supernova progenitors.

Contribution

It provides the first detection of Cr lines in three supernova remnants and links Cr and Fe line properties to nucleosynthesis and explosion mechanisms.

Findings

Cr lines confirmed in W49B, discovered in Cas A, Tycho, Kepler

Positive correlation between Cr and Fe line energies

Cr/Fe EW ratio as a probe for progenitor properties

Abstract

We performed a Cr-K emission line survey in young supernova remnants (SNRs) with the Chandra archival data. Our sample includes W49B, Cas A, Tycho and Kepler. We confirmed the existence of the Cr line in W49B and discovered this emission line in the other three SNRs. The line center energies, equivalent widths (EWs) and fluxes of the Cr lines are given. The Cr in Cas A is in a high ionization state while that in Tycho and Kepler is in a much lower one. We find a good positive correlation between Cr and Fe line center energies, suggesting a common origin of Cr and Fe in the nucleosynthesis, which is consistent with the theoretical predictions. We propose that the EW ratio between Cr and Fe can be used as a supplementary constraint on the progenitors' properties and the explosion mechanism.