Prompt Ia Supernovae Are Significantly Delayed

TL;DR

This study measures the delay time of type Ia supernovae using a new spatial analysis technique, revealing a significant delay of 200-500 million years, which impacts understanding of their progenitors.

Contribution

The paper introduces a novel method focusing on relevant host regions to accurately measure SNe Ia delay times, providing new constraints on progenitor models.

Findings

Prompt SNe Ia have a delay of 200-500 million years.

Majority of SNe Ia progenitors may have low-mass main-sequence companions.

SNe Ia rate correlates with white dwarf formation rate.

Abstract

The time delay between the formation of a population of stars and the onset of type Ia supernovae (SNe Ia) sets important limits on the masses and nature of SN Ia progenitors. Here we use a new observational technique to measure this time delay by comparing the spatial distributions of SNe Ia to their local environments. Previous work attempted such analyses encompassing the entire host of each SN Ia, yielding inconclusive results. Our approach confines the analysis only to the relevant portions of the hosts, allowing us to show that even so-called "prompt" SNe Ia that trace star-formation on cosmic timescales exhibit a significant delay time of 200-500 million years. This implies that either the majority of Ia companion stars have main-sequence masses less than 3 solar masses, or that most SNe Ia arise from double-white dwarf binaries. Our results are also consistent with a SNe Ia rate that traces the white dwarf formation rate, scaled by a fixed efficiency factor.