Dark-ages reionization and galaxy formation simulation – X. The small contribution of quasars to reionization

Abstract Motivated by recent measurements of the number density of faint AGN at high redshift, we investigate the contribution of quasars to reionization by tracking the growth of central supermassive black holes in an update of the Meraxes semi-analytic model. The model is calibrated against the observed stellar mass function at z ∼ 0.6–7, the black hole mass function at z ≲ 0.5, the global ionizing emissivity at z ∼ 2–5 and the Thomson scattering optical depth. The model reproduces a Magorrian relation in agreement with observations at z