Escape fraction of ionizing photons from objects of different masses at various redshifts. The curves from bottom to top correspond to baryonic masses 10⁴, 10⁵, 10⁶, 10⁷, 10⁸, and 10⁹ M_☉ and are obtained from equilibrium ionization profiles similar to Fig. 5. The heavy solid line shows the fitting formula log f_esc = 1.92{exp [−(z − 10)²/1510] − 1} for z > 10. For comparison, the dashed line shows the theoretical estimate of the escape fraction from the disk of the Milky Way galaxy (Dove & Shull 1994), and the dotted line shows the observed value of the escape fraction in four nearby starburst galaxies (Leitherer et al. 1996).