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

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 \textit{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 \textit{Capotauro} is a pair-instability supernova (PISN) originating from a massive (\(\sim250\)–\(260\,M_\odot\)), 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.