Hunting for the First Explosions at the High-Redshift Frontier

TL;DR

This paper explores the possibility that extremely high-redshift galaxy candidates detected by JWST could be hyper-energetic transient events like pair-instability supernovae, providing insights into the first star formation epoch.

Contribution

It introduces a cosmological simulation-based analysis of PISNe at z~30-40, suggesting JWST could detect such events, thus offering a new method to study early universe phenomena.

Findings

JWST has a chance to detect PISNe at z>20

Simulations show PISNe can occur at z~30-40 in overdense regions

Detection of such events would reveal first star formation epoch

Abstract

The James Webb Space Telescope (JWST) has spectroscopically confirmed galaxies up to $z\sim14$, 300 Myr after the Big Bang, and several candidates have been discovered at $z\sim15-25$, with one candidate as high as $z\sim30$, only 100 Myr after the Big Bang. Such objects are unexpected, since theoretical studies have not predicted the existence of detectable galaxies at $z\sim30$. While any $z\sim30$ candidates may be contaminants at lower redshifts, we explore whether such extreme redshift sources could be consistent with hyper-energetic transient events linked to the formation of the first, metal-free, stars. Specifically, we consider pair-instability supernovae (PISNe), a predicted class of extreme thermonuclear explosions that leave no remnant behind. Using cosmological simulations, we investigate an overdense cosmic region, where star formation and subsequent PISNe occur at $z\sim30-40$, even within standard cosmology. Assessing the likelihood of such a region, the corresponding number of PISNe at $z\gtrsim20$, and their observed flux, we find that JWST has a non-negligible chance to detect a PISN event at extremely high redshifts. If a transient event were confirmed at $z\sim30$, this would provide a direct glimpse into the epoch of first star formation, dramatically extending the empirical reach of astronomy.