Using cosmological particle hydrodynamical simulations and uniform ultraviolet backgrounds, we compare Lyman-α forest flux spectra predicted by the conventional cold dark matter (CDM) model, the free-particle wave dark matter (FPψDM) model and extreme-axion wave dark matter (EAψDM) models of different initial axion field angles against the BOSS Lyman-α forest absorption spectra with a fixed boson mass m b ∼ 10 −22 eV. We recover results reported previously (Iršič et al. 2017b;Armengaud et al. 2017) that the CDM model agrees better with the BOSS data than the FPψDM model by a large margin, and we find the difference of total χ 2 's is 120 for 420 data bins. These previous results demand a larger boson mass by a factor > 10 to be consistent with the date and are in tension with the favoured value determined from local satellite galaxies. We however find that such tension is removed as some EAψDM models predict Lyman-α flux spectra agreeing better with the BOSS data than the CDM model, and the difference of total χ 2 's can be as large as 24 for the same bin number. This finding arises with no surprise since EAψDM models have unique spectral shapes with spectral bumps in excess of the CDM power near the small-scale cutoff typical of ψDM linear matter power spectra as well as more extended cutoffs than FPψDM (Zhang & Chiueh 2017a,b).

We compare numerical methods for solving the radiative transfer equation in the context of the photoionization of intergalactic gaseous hydrogen and helium by a central radiating source. Direct integration of the radiative transfer equation and solutions using photon packets are examined, both for solutions to the time-dependent radiative transfer equation and in the infinite-speed-of-light approximation. The photon packet schemes are found to be more generally computationally efficient than a direct integration scheme. Whilst all codes accurately describe the growth rate of hydrogen and helium ionization zones, it is shown that a fully time-dependent method is required to capture the gas temperature and ionization structure in the near zone of a source when an ionization front expands at a speed close to the speed of light. Applied to Quasi-Stellar Objects in the Epoch of Reionization (EoR), temperature differences as high as 5 × 104 K result in the near-zone for solutions of the time-dependent radiative transfer equation compared with solutions in the infinite-speed-of-light approximation. Smaller temperature differences are found following the nearly full photoionization of helium in gas in which the hydrogen was already ionized and the helium was singly ionized. Variations found in the temperature and ionization structure far from the source, where the gas is predominantly neutral, may affect some predictions for 21-cm EoR experiments.

We compare numerical methods for solving the radiative transfer equation in the context of the photoionization of intergalactic gaseous hydrogen and helium by a central radiating source. Direct integration of the radiative transfer equation and solutions using photon packets are examined, both for solutions to the time-dependent radiative transfer equation and in the infinite-speed-of-light approximation. The photon packet schemes are found to be more generally computationally efficient than a direct integration scheme. Whilst all codes accurately describe the growth rate of hydrogen and helium ionization zones, it is shown that a fully time-dependent method is required to capture the gas temperature and ionization structure in the near zone of a source when an ionization front expands at a speed close to the speed of light. Applied to Quasi-Stellar Objects in the Epoch of Reionization (EoR), temperature differences as high as 5×10 4 K result in the near-zone for solutions of the time-dependent radiative transfer equation compared with solutions in the infinite-speed-of-light approximation. Smaller temperature differences are found following the nearly full photoionization of helium in gas in which the hydrogen was already ionized and the helium was singly ionized. Variations found in the temperature and ionization structure far from the source, where the gas is predominantly neutral, may affect some predictions for 21-cm EoR experiments.