Finding high-redshift dark stars with the James Webb Space Telescope

TL;DR

This paper assesses the potential for detecting high-redshift dark stars with JWST, finding they are generally too faint but could be observed via gravitational lensing, and may influence galaxy spectra if sufficiently abundant.

Contribution

It introduces a method to detect high-redshift dark stars using gravitational lensing with JWST and explores their possible impact on galaxy spectra.

Findings

Dark stars at z>6 are too faint for direct JWST detection.

Gravitational lensing by galaxy clusters can make certain dark stars observable up to z=10.

Dark stars could significantly affect the spectra of early galaxies if they constitute at least 1% of stellar mass.

Abstract

The first stars in the history of the Universe are likely to form in the dense central regions of 10^5-10^6 Msolar cold dark matter halos at z=10-50. The annihilation of dark matter particles in these environments may lead to the formation of so-called dark stars, which are predicted to be cooler, larger, more massive and potentially more long-lived than conventional population III stars. Here, we investigate the prospects of detecting high-redshift dark stars with the upcoming James Webb Space Telescope (JWST). We find that dark stars at z>6 are intrinsically too faint to be detected by JWST. However, by exploiting foreground galaxy clusters as gravitational telescopes, certain varieties of cool (Teff < 30000 K) dark stars should be within reach at redshifts up to z=10. If the lifetimes of dark stars are sufficiently long, many such objects may also congregate inside the first galaxies. We demonstrate that this could give rise to peculiar features in the integrated spectra of galaxies at high redshifts, provided that dark stars make up at least 1 percent of the total stellar mass in such objects.