Spectroscopic Supermassive Dark Star candidates

Abstract

Dark Stars (DSs), i.e., early stars composed almost entirely of hydrogen and helium but powered by Dark Matter (DM), could form in zero metallicity clouds located close to the center of high redshift DM halos. In 2023, three of us identified (in a PNAS work) the first three photometric DS candidates: JADES-GS-z11-0, JADES-GS-z12-0, and JADES-GS-z13-0. We report here our results of a follow-up analysis based on available NIRSpec JWST data. We find that JADES-GS-z11-0 and JADES-GS-z13-0 are spectroscopically consistent with a DS interpretation. Moreover, we find two additional spectroscopic DS candidates: JADES-GS-z14-0 and JADES-GS-z14-1, with the former being the second most distant luminous object ever observed. We furthermore identify, in the spectrum of JADES-GS-z14-0, a tentative feature ( S / N ∼ 2 ) indicative of the smoking gun signature of DSs: the He II λ 1640 absorption line. In view of ALMA’s recent identification of a probable O III nebular emission line in the spectrum of JADES-GS-z14-0, the simple interpretation of this object as an isolated DS is unlikely. If both spectral features survive follow-up observations, it would imply a DS embedded in a metal rich environment, requiring theoretical refinements of the formation of evolution of DSs, which in previous studies were assumed to form in isolation, without any companions.