Evolution of the intergalactic medium - What happened during the epoch Z = 3-10?

The authors attempt to model in a consistent way the thermal and dynamical history of the intergalactic medium from the era of reheating (z = 10 - 5) to the present, and to provide a unified explanation for the origin of ordinary galaxies, blue compact objects and Lyα clouds. First, the thermal history of the intergalactic medium is explored, assuming it to be uniform in temperature and density, considering radiative and Compton cooling, adiabatic cooling, and the heating produced by the diffuse UV flux and shock heating. Second, the paper investigates the formation and the evolution of intergalactic clouds. It is suggested that massive shells fragment gravitationally and produce clouds with masses 1011. 3 ⪆ M/Mₛun; ⪆ 109. 5 which collapse to galaxies; those with 109. 5 - 108. 5Mₛun; have collapsed recently and are observed as young blue compact galaxies. Still lower mass shells would have formed clouds in the mass range 108. 5 - 106. 0Mₛun; which are now expanding and detected as the quasar Lyα absorbers.