Can Dark Stars Account for the Star Formation Efficiency Excess at Very High Redshifts?

Abstract

The James Webb Space Telescope (JWST) has recently conducted observations of massive galaxies at high redshifts, revealing a notable anomaly in their star formation efficiency (SFE). Motivated by the recent identification of three ~106M⊙ dark star candidates, we investigate whether dark stars can be the origin of the SFE excess. It turns out that the excess can be reproduced by a group of dark stars with M ≳ 103M⊙, because of their domination in generating primary UV radiation in high-redshift galaxies. The genesis of these dark stars is attributed to the capture of weakly interacting massive particles within a mass range of tens of gigaelectronvolts to a few teraelectronvolts. However, if the top-heavy initial mass function of dark stars holds up to ~105M⊙, the relic black holes stemming from their collapse would be too abundant to be consistent with the current observations of massive compact halo objects. We thus suggest that just a small fraction of SFE excess may be contributed by the very massive dark stars, with the majority likely originating from other sources, such as the Population III stars, in view of their rather similar UV radiation efficiencies.