Possible evidence for a pair-instability supernova nature of ultra-early JWST sources

TL;DR

Recent JWST ultra-high redshift sources may be explained as pair-instability supernovae from Population III stars, challenging the galaxy formation paradigm and emphasizing the need for transient contamination considerations.

Contribution

This paper proposes the novel hypothesis that some ultra-high redshift JWST sources are actually PISNe, supported by modeling their light curves and spectra.

Findings

A PISN at z~15 can match observed brightness and spectrum.

Variability suggests a transient event rather than a galaxy.

Alternative explanations like brown dwarfs are less consistent with data.

Abstract

Recent JWST observations have revealed a population of unexpectedly bright sources at ultra-high redshift ($z > 15$), challenging current models of early galaxy formation. One extreme example is 'Capotauro', an F356W-dropout identified in the CEERS survey and initially interpreted as a luminous galaxy at $z\sim30$, but subsequently found to be variable over an $\sim 800$ day baseline. Motivated by this variability, we explore the alternative hypothesis that Capotauro is a pair-instability supernova (PISN) originating from a massive ($250-260\,M_\odot$), metal-free star. Using state-of-the-art PISN light curves, spectral energy distributions, and synthetic spectra, we show that a PISN at $z\simeq 15$ can plausibly reproduce the observed brightness, temporal evolution, photometry, and NIRSpec spectrum. We compare this scenario with alternative interpretations, including a local Y0 brown dwarf, and discuss observational tests to discriminate among them. If confirmed, this event would provide a rare window onto Population III stars, and highlights the importance of transient contamination in ultra-high redshift galaxy samples.