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Updated: Aug 19, 2026

Bringing the Visible Universe into Focus with Robo-AO
Published on: February 12, 2013
The universe at z > 5: when and how did the "dark age" end?
1Institute of Astronomy, Madingley Road, Cambridge, CB3 OHA, United Kingdom.
Abstract:
This paper considers how the first subgalactic structures produced the UV radiation that ionized the intergalactic medium before z = 5 and the "feedback" effects of the UV radiation on structure formation. The first "pregalaxies" may eventually be detectable by their direct UV emission, with characteristic spectral features at Lyman alpha; high-z supernovae may also be detectable. Other probes of the intergalactic medium beyond z = 5, and of the epochs of reheating and reionization, are discussed, along with possible links between the diffusion of pregalactic metals and the origin of magnetic fields.
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