Can Dark Stars account for the star formation efficiency excess at very high redshifts?

TL;DR

This paper explores whether dark stars can explain the star formation efficiency excess observed at high redshifts, suggesting a partial contribution from dark stars and highlighting constraints from relic black hole observations.

Contribution

It proposes that dark stars with masses above 10^3 solar masses can account for the SFE excess, linking their formation to WIMP capture and discussing observational constraints.

Findings

Dark stars can reproduce the SFE excess through their UV radiation dominance.

Relic black hole abundance constraints limit the contribution of very massive dark stars.

Most of the SFE excess likely originates from Population III stars rather than dark stars.

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 $\sim 10^{6}M_\odot$ 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 $M \gtrsim 10^{3}\, \rm M_{\odot}$, 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 (WIMPs) within a mass range of tens of GeV to a few TeV. However, if the top-heavy initial mass function of dark stars holds up to $\sim 10^{5}M_\odot$, the relic black holes stemming from their collapse would be too abundant to be consistent with the current observations of Massive Compact Halo Objects (MACHOs). We thus suggest that just a small fraction of SFE excess may be contributed by the very massive dark stars and the majority likely originated from other reasons such as the Population III stars in view of their rather similar UV radiation efficiencies.