Principal Investigator
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Project Title
| Ionisation of a Clumpy Universe by Population III Stars |
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Brief Description for General Publications
The re-ionisation of the universe is currently a problem of great interest in cosmology. Early models assumed a homogeneous Inter-Galactic Medium (IGM) which was exposed to UV radiation. More recent studies have focused on density inhomogeneities and the effects of the increased rate of recombination in more dense regions, and shown that these can influence the observed cosmic background spectrum. The important problem of the evolution of expanding ionisation regions which subsequently overlap at a critical redshift has been addressed. All these models have, however, assumed 1-D radiative transfer, and do not address the problem of how ionisation proceeds in a more realistic 3-D scenario where the radiation field is anisotropic, and radiation can escape preferentially in certain directions. We propose to carry out a study of the time evolution of the thermal and ionisation properties of a clumpy IGM early in the history of the universe when the composition was mainly hydrogen and helium, and the first luminous sources were formed. The calculation will be carried out by solving the cosmological radiative transfer equations in a model universe which includes cold dark matter and a cosmological constant where the baryonic density distribution, and the distribution of stellar UV sources and black holes is given by hydrodynamic simulations. |