# Nebular Spectra of 111 Type Ia Supernovae Disfavor Single Degenerate Progenitors

## TL;DR

This study analyzes 227 nebular spectra of 111 Type Ia supernovae to constrain progenitor models, finding no evidence for certain companion scenarios and establishing upper limits on their occurrence rates.

## Contribution

It provides the first comprehensive statistical constraints on Type Ia supernova progenitors using nebular spectra and introduces a new nebular phase Phillips relation.

## Key findings

- No evidence of stripped companion emission in spectra
- Upper limit of <5.5% on H-rich non-degenerate progenitors
- Upper limit of <6.4% on He star progenitors

## Abstract

We place statistical constraints on Type Ia supernova (SN Ia) progenitors using 227 nebular phase spectra of 111 SNe Ia. We find no evidence of stripped companion emission in any of the nebular phase spectra. Upper limits are placed on the amount of mass that could go undetected in each spectrum using recent hydrodynamic simulations. With these null detections, we place an observational $3\sigma$ upper limit on the fraction of SNe Ia that are produced through the classical H-rich non-degenerate companion scenario of < 5.5%. Additionally, we set a tentative $3\sigma$ upper limit on He star progenitor scenarios of < 6.4%, although further theoretical modelling is required. These limits refer to our most representative sample including normal, 91bg-like, 91T-like, and "Super Chandrasekhar" \sne but excluding SNe Iax and SNe Ia-CSM. As part of our analysis, we also derive a Nebular Phase Phillips Relation, which approximates the brightness of a SN Ia from $150-500$~days after maximum using the peak magnitude and decline rate parameter $\Delta m_{15} (B)$.