Empirical Delay Time Distributions of Type Ia Supernovae From The Extended GOODS/HST Supernova Survey

TL;DR

This study uses HST data to empirically determine the delay-time distribution of Type Ia supernovae, finding it predominantly occurs 3-4 Gyrs after star formation, with implications for understanding supernova progenitors and cosmic evolution.

Contribution

It provides the first empirical constraint on the delay-time distribution of SNe Ia over a broad redshift range using a Markov chain Monte Carlo analysis.

Findings

Delay-time distribution is confined to 3-4 Gyrs with >95% confidence.

High-redshift (z>1.2) SNe Ia show a delay-time distribution inconsistent with prompt explosions.

Lower-redshift (z<1) SNe Ia suggest a prompt component, aligning with local observations.

Abstract

Using the Hubble Space Telescope ACS imaging of the GOODS North and South fields during Cycles 11, 12, and 13, we derive empirical constraints on the delay-time distribution function for type Ia supernovae. We extend our previous analysis to the three-year sample of 56 SNe Ia over the range 0.2<z<1.8, using a Markov chain Monte Carlo to determine the best-fit unimodal delay-time distribution function. The test, which ultimately compares the star formation rate density history to the unbinned volumetric SN Ia rate history from the GOODS/HST-SN survey, reveals a SN Ia delay-time distribution that is tightly confined to 3-4 Gyrs (to >95% confidence). This result is difficult to resolve with any intrinsic delay-time distribution function (bimodal or otherwise), in which a substantial fraction (e.g., >10%) of events are ``prompt'', requiring less than approximately 1 Gyr to develop from formation to explosion. The result is, however, strongly motivated by the decline in the number of SNe Ia at z>1.2. Sub-samples of the HST-SN data confined to lower redshifts (z<1) show plausible delay-time distributions that are dominated by prompt events, which is more consistent with results from low-redshift supernova samples and supernova host galaxy properties. Scenarios in which a substantial fraction of z>1.2 supernovae are extraordinarily obscured by dust may partly explain the differences in low-z and high-z results. Other possible resolutions may include environmental dependencies (such as gas-phase metallicity) that affect the progenitor mechanism efficiency, especially in the early universe.