A Pilot Search for Population III Supernova Candidates in the Spitzer/IRAC Dark Field

TL;DR

This study conducted a systematic search for high-redshift Population III supernovae candidates using deep, multi-epoch Spitzer/IRAC data over 2.2 years, but found no plausible candidates, setting upper limits on their occurrence.

Contribution

First systematic search for Population III supernova candidates in the infrared using multi-epoch data, establishing upper limits on their rate.

Findings

No high-redshift supernova candidates identified.

Set a 95% confidence upper limit of 23 per square degree per year.

Demonstrated the effectiveness of multi-epoch infrared surveys for transient detection.

Abstract

We have undertaken a systematic search for candidate supernovae from high-redshift Population III stars in a field that has been observed with repeated imaging on a cadence of 2-3 weeks over a 2.2 year baseline, the Spitzer/IRAC Dark Field. The individual epochs reach a typical 5-sigma depth of 1 uJy in IRAC Channel 1 (3.6 um). Requiring a minimum of four epochs coverage, the total effective area searched is 214 sq arcminutes. The unprecedented depth and multi-epochal nature of these data make it ideal for a first foray to detect transient objects which may be candidate luminous Pair Instability Supernovae from the primordial-metallicity first stars. The search was conducted over a broad range of timescales, allowing for different durations of the putative candidates' light curve plateau phases. All candidates were vetted by inspection of the Spitzer imaging data, as well as deep HST/ACS F814W imaging available over the full field. While many resolved-source objects were found with Spitzer variability, no transient objects could plausibly be identified as high-redshift supernovae candidates. The resulting 95% confidence level upper limit is 23/sq deg/yr, for sources with plateau timescales under 400/(1+z) days and brightnesses above ~1 uJy.