Abstract:
The star-formation activity of the Universe has gone through strong
changes from redshifts of z~3 until present day. Information about the
gas content of typical star-forming galaxies responsible for these
changes has so far largely been missing. In this talk I present several
theoretical approaches to make predictions for and support upcoming
observations of the gas content of high redshift galaxies with ALMA and
SKA. First, I present a novel method to indirectly estimate the HI and
H2 content of a sample of ~20000 galaxies covering a wide range of
redshifts and highlight the HI and H2 evolution in this sample of
galaxies. Second, I present a new model in which I explicitly track the
formation of molecular hydrogen and implement a physically-motivated
H2-based star formation recipe within a semi-analytic cosmological
galaxy formation model. I discuss our predictions for the atomic and
molecular content of galaxies, how they evolve and how they constrain
our understanding of galaxy formation and evolution. Third, I present a
combination of this model of galaxy formation with a three-dimensional
radiative transfer code. I discuss the CO, HCN, C, [CII], and [OI]
emission from galaxies and use this tool to study how the detailed gas
properties of galaxies during cosmic noon compares to galaxies in the
local Universe and make direct predictions for ALMA observations.