A New Determination of the High Redshift Type Ia Supernova Rates with the Hubble Space Telescope Advanced Camera for Surveys

TL;DR

This paper introduces a Bayesian photometric method to measure high-redshift Type Ia supernova rates using HST data, enabling rate estimation without extensive spectroscopic follow-up, and analyzes the evolution of these rates with redshift.

Contribution

The paper presents a novel Bayesian technique for identifying Type Ia supernovae from photometric data alone, improving rate measurements at high redshift without requiring spectroscopic confirmation.

Findings

Measured supernova rate up to redshift 1.7.

Method yields smaller or comparable uncertainties to previous work.

Data do not distinguish between different models of rate evolution.

Abstract

We present a new measurement of the volumetric rate of Type Ia supernova up to a redshift of 1.7, using the Hubble Space Telescope (HST) GOODS data combined with an additional HST dataset covering the North GOODS field collected in 2004. We employ a novel technique that does not require spectroscopic data for identifying Type Ia supernovae (although spectroscopic measurements of redshifts are used for over half the sample); instead we employ a Bayesian approach using only photometric data to calculate the probability that an object is a Type Ia supernova. This Bayesian technique can easily be modified to incorporate improved priors on supernova properties, and it is well-suited for future high-statistics supernovae searches in which spectroscopic follow up of all candidates will be impractical. Here, the method is validated on both ground- and space-based supernova data having some spectroscopic follow up. We combine our volumetric rate measurements with low redshift supernova data, and fit to a number of possible models for the evolution of the Type Ia supernova rate as a function of redshift. The data do not distinguish between a flat rate at redshift > 0.5 and a previously proposed model, in which the Type Ia rate peaks at redshift >1 due to a significant delay from star-formation to the supernova explosion. Except for the highest redshifts, where the signal to noise ratio is generally too low to apply this technique, this approach yields smaller or comparable uncertainties than previous work.