The cool side of high redshift Universe

The unprecedented sensitivity reached by the Atacama Large Millimeter/submillimeter Array (ALMA)
will revolutionize our knowledge of the high redshift Universe. In particular, ALMA will allow the detection
of metal and molecular lines (e.g. [CII]158 micron, CO rotational transitions) arising from the first galaxies
formed after the Big-Bang. These lines represent a powerful tool to characterize the physical properties
(e.g. gas density, temperature, metallicity) of the interstellar medium (ISM) and of molecular clouds (MCs)
whose features are currently scarcely constrained in high-z sources.

I will present a new class of models based on high-resolution cosmological simulations that allow to estimate the
expected luminosity of far-infrared lines arising from cold neutral and molecular gas residing in Lyman Alpha Emitters.
This work is fundamental to interpret the first ALMA results and to design future ALMA observations.