Dark matter capture in the first stars: a power source and limit on stellar mass

Abstract

The annihilation of weakly interacting massive particles can provide an important heatsource for the first (Pop III, ‘Pop’ standing for ‘population’) stars, potentially leading to anew phase of stellar evolution known as a ‘dark star’. When dark matter (DM)capture via scattering off baryons is included, the luminosity from DM annihilationmay dominate over the luminosity due to fusion, depending on the DM densityand scattering cross section. The influx of DM due to capture may thus prolongthe dark star phase of stellar evolution as long as the ambient DM density ishigh enough. Comparison of DM luminosity with the Eddington luminosity forthe star may constrain the stellar mass of zero-metallicity stars. Alternatively, ifsufficiently massive Pop III stars are found, they might be used to bound dark matterproperties.