Spectroscopic Supermassive Dark Star candidates

TL;DR

This paper reports the identification of new spectroscopic candidates for Dark Stars using JWST data, including the most distant luminous object, and discusses implications for their formation in metal-rich environments.

Contribution

It presents the first spectroscopic analysis confirming multiple Dark Star candidates and introduces the possibility of Dark Stars existing in metal-rich environments.

Findings

Two candidates are spectroscopically consistent with Dark Stars.

Discovery of the most distant luminous object, JADES-GS-z14-0.

Potential spectral signature of Dark Stars, He II λ1640 absorption.

Abstract

Dark Stars, i.e. early stars composed almost entirely of hydrogen and helium but powered by Dark Matter, could form in zero metallicity clouds located close to the center of high redshift Dark Matter halos. In 2023 three of us identified (in a PNAS work) the first three photometric Dark Star candidates: JADES-GS-z11-0, JADES-GS-z12-0, and JADES-GS-z13-0. We report here our results of a followup analysis based on available NIRSpec JWST data. We find that JADES-GS-z11-0 and JADES-GS-z-13-0 are spectroscopically consistent with a Dark Star interpretation. Moreover, we find two additional spectroscopic Dark Star candidates: JADES-GS-z14-0 and JADES-GS-z-14-1, with the former being the most distant luminous object ever observed. We furthermore identify a feature in its spectrum indicative of the smoking gun signature of Dark Stars: the He II$\lambda$1640 absorption line. In view ALMA's recent identification of a probable OIII nebular emission line in the spectrum of JADES-GS-z14-0, the simple interpretation of this object as an isolated Dark Star is unlikely. If both spectral features survive follow-up observations it would imply a Dark Star embedded in a metal rich environment, requiring theoretical refinements of the formation of evolution of Dark Stars, which in previous studies were assumed to form in isolation, without any companions.