  We present an Analytic Model of Intergalactic-medium and GAlaxy evolution
since the dark ages. AMIGA is in the spirit of the popular semi-analytic models
of galaxy formation, although it does not use halo merger trees but
interpolates halo properties in grids that are progressively built. This
strategy is less memory-demanding and allows one to start the modeling at
redshifts high enough and halo masses low enough to have trivial boundary
conditions. The number of free parameters is minimized by making the causal
connection between physical processes usually treated as independent from each
other, which leads to more reliable predictions. But the strongest points of
AMIGA are: i) the inclusion of molecular cooling and metal-poor, population III
(Pop III) stars, with the most dramatic feedback, and ii) the accurate
follow-up of the temperature and volume filling factor of neutral, singly, and
doubly ionized regions, taking into account the distinct halo mass functions in
those environments. We find the following general results. Massive Pop III
stars determine the IGM metallicity and temperature, and the growth of
spheroids and disks is self-regulated by that of massive black holes developed
from the remnants of those stars. Yet, the properties of normal galaxies and
active galactic nuclei appear to be quite insensitive to Pop III star
properties owing to the much higher yield of ordinary stars compared to Pop III
stars and the dramatic growth of MBHs when normal galaxies begin to develop,
which cause the memory loss of the initial conditions.
