Evolution of the First Stars with Dark Matter Burning

Abstract

Recent theoretical studies have revealed the possibly important role of the capture and annihilation process of weakly interacting massive particles (WIMPs) for the first stars. Using new evolutionary models of metal-free massive stars, we investigate the impact of such ``dark matter burning'' for the first stars in different environments of dark matter (DM) halos, in terms of the ambient WIMP density (rho_chi). We find that, in agreement with existing literature, stellar life times can be significantly prolonged for a certain range of rho_\chi (i.e., 10^{10} ~ < \rho_\chi GeV/cm3 ~ < 10^{11} with the current upper limit for the spin-dependent elastic scattering cross section sigma = 5*10^{-39} cm2}). This greatly enhances the role of rotationally induced chemical mixing in rotating stars, in favor of abundant production of primary nitrogen, massive helium stars and long gamma-ray bursts, from the first stars. We also find that stars with rho_chi > 2*10^{11} GeV/cm3 may not undergo nuclear burning stages, confirming the previous work, and that ionizing photon fluxes from such DM supported stars are very weak. Delayed metal enrichment and slow reionization in the early universe would have resulted if most of the first stars had been born in DM halos with such high rho_\chi, unless it had been lowered significantly below the threshold for efficient DM burning on a short time scale.