A self‐consistent formalism to jointly study cosmic reionization and thermal history of the intergalactic medium (IGM) in a ΛCDM cosmology is presented. The model implements most of the relevant physics governing these processes, such as the inhomogeneous IGM density distribution, three different classes of ionizing photon sources (massive PopIII stars, PopII stars and QSOs), chemical feedback for PopIII → PopII transition and radiative feedback inhibiting star formation in low‐mass galaxies. Using our model, we find out the range of reionization histories which can match a wide variety of data sets simultaneously. The constraints from our analysis imply that hydrogen reionization starts around z ≈ 15, driven by the metal‐free PopIII stars (with normal Salpeter‐like IMF), while it is 90 per cent complete by z ≈ 10. The contribution of the PopIII stars start decreasing at z < 10 because of radiative and chemical feedbacks and hence the reionization is extended considerably completing only by z ≈ 6. The combination of different data sets still strongly favour a non‐zero contribution from metal‐free stars, with star‐forming efficiencies larger than 2 per cent.

This content is only available via PDF.
You do not currently have access to this content.