The observational signatures of high-redshift dark stars

The annihilation of dark matter particles in the centers of minihalos may lead to the formation of so-called dark stars, which are 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 both existing and upcoming telescopes. We find that individual dark stars with masses below ~1e3 Msolar are intrinsically too faint even for the upcoming James Webb Space Telescope (JWST). However, by exploiting foreground galaxy clusters as gravitational telescopes, certain varieties of such dark stars should be within reach of the JWST at z=10. If more massive dark stars are able to form, they may be detectable by JWST even in the absence of lensing. In fact, some of the supermassive (~1e7 Msolar) dark stars recently proposed are sufficiently bright at z=10 to be detectable even with existing facilities, like the Hubble Space Telescope and 8-10 m telescopes on the ground. Finally, we argue that since the hottest dark stars (Teff > 30000 K) can produce their own HII regions, they may be substantially brighter than what estimates based on stellar atmosphere spectra would suggest.
Comment: 5 pages, 1 figure, conference proceedings from Identification of Dark Matter 2010, Montpellier, France