Science with an ngVLA. Cold gas in High-z Galaxies: The molecular gas
  budget
  The goal of this science case is to accurately pin down the molecular gas
content of high redshift galaxies. By targeting the CO ground transition, we
circumvent uncertainties related to CO excitation. The ngVLA can observe the
CO(1-0) line at virtually any $z>1.5$, thus exposing the evolution of gaseous
reservoirs from the earliest epochs down to the peak of the cosmic history of
star formation. The order-of-magnitude improvement in the number of CO
detections with respect to state-of-the-art observational campaigns will
provide a unique insight on the evolution of galaxies through cosmic time.
