Star formation histories versus redshift: Consequences for overall metallicity and deuterium destruction

The flood of new data on deep surveys, and above all the CFRS (Canada-France-Redshift-Survey), has had a great impact on studies of galactic evolution. On the basis of cosmological models consistent with the improved values of the Hubble parameter, different star formation histories are tested against the observed UV, B and IR broad band comoving luminosity densities. Using these spectrophotometric results, we analyze the global metal enrichment with the help of chemical evolutionary models and we discuss the pertinence of different metallicity tracers (quasar absorption systems and clusters of galaxies) as representative of the bulk chemical evolution of the Universe. Moreover, as deuterium is very fragile, this isotope is destroyed in all stars and its evolution is particularly sensitive to the history of star formation. Relying on models constrained to fit the solar vicinity, it is shown that models with high D destruction corresponding to a large decrease of the star formation rate (SFR) from z = 1.5 to 0 are in good agreement with spectrophotometric data. In contrast, low D destruction models which require only a moderate variation of the SFR in the same redshift range seem to encounter difficulties in matching the evolution of the luminosity densities (UV, B and IR) versus redshift. The sensitivity of the results with the cosmological models of the universe is discussed.