Super-Chandrasekhar SNe Ia Strongly Prefer Metal-Poor Environments

TL;DR

Super-Chandrasekhar Type Ia Supernovae predominantly occur in metal-poor environments, especially in the outer regions of their host galaxies, suggesting low metallicity as a key factor in their progenitor evolution.

Contribution

This study provides quantitative evidence linking super-Chandrasekhar SNe Ia to metal-poor environments by analyzing their explosion sites within host galaxies.

Findings

Most super-Chandrasekhar SNe Ia explode in the outer, metal-poor regions of host galaxies.

Explosion sites are often outside 99% of the host galaxy's light, indicating low metallicity environments.

The correlation suggests metallicity plays a significant role in the progenitor scenarios of these supernovae.

Abstract

We discuss the emerging trend that super-Chandrasekhar Type Ia Supernovae (SCSNe) with progenitor mass estimates significantly exceeding 1.4 M_sun tend to explode in metal-poor environments. While Taubenberger et al. 2011 noted that some of the SCSNe host galaxies are relatively metal-poor, we focus quantitatively on their locations in the hosts to point out that in three out of four cases, the SCSNe explosions occurred in the outer edge of the disks of their hosts. It is therefore very likely that their progenitors had far lower metallicities than those implied by the metallicity of their hosts' central regions. In two cases (SN 2003fg and SN 2009dc) the explosion sites were outside 99% of the host's light, and in one case (SN 2006gz) the host's radial metallicity slope indicates that the explosion site is in a metal-poor region. The fourth case (SN 2007if) has the lowest spectroscopically measured SN Ia host metallicity (Childress et al. 2011. It may be possible to explain each of these unusually bright events through some progenitor scenario specific to that case, but a much simpler and straightforward conclusion would be to ascribe the controlling factor to the only physical aspect they have in common --- metal poor environments.