The Source Density and Observability of Pair-Instability Supernovae from the First Stars

TL;DR

This paper estimates the occurrence rate and observability of pair-instability supernovae from the first stars, highlighting their scarcity as the main challenge for detection with JWST and proposing an optimized search strategy.

Contribution

It provides the first semi-analytic estimate of PISNe rates from first stars, incorporating feedback effects and suggesting effective observational strategies.

Findings

Estimated up to 0.2 PISNe per JWST field at any time.

Feedback can reduce PISNe rates to as low as one per 4000 fields.

Scarcity, not faintness, limits PISNe detection from the first stars.

Abstract

Theoretical models predict that some of the first stars ended their lives as extremely energetic pair-instability supernovae (PISNe). With energies approaching 10^53 ergs, these supernovae are expected to be within the detection limits of the upcoming James Webb Space telescope (JWST), allowing observational constraints to be placed on the properties of the first stars. We estimate the source density of PISNe using a semi-analytic halo mass function based approach, accounting for the effects of feedback from star formation on the PISN rates using cosmological simulations. We estimate an upper limit of ~0.2 PISNe per JWST field of view at any given time. Feedback can reduce this rate significantly, e.g., lowering it to as little as one PISN per 4000 JWST fields of view for the most pessimistic explosion models. We also find that the main obstacle to observing PISNe from the first stars is their scarcity, not their faintness; exposures longer than a few times 10^4s will do little to increase the number of PISNe found. Given this we suggest a mosaic style search strategy for detecting PISNe from the first stars. Even rather high redshift PISNe are unlikely to be missed by moderate exposures, and a large number of pointings will be required to ensure a detection.