Enhanced Far-IR Line Emission at High-Z: Implications for SPICA

Recent observations of the fine structure line [CII]158μm in high redshift galaxies have shown that this line is significantly stronger in distant galaxies than in local counterparts with the same far-IR luminosity. This enhancement at high-z probably applies also to other far-IR fine structure lines. This result suggests that SPICA, and in particular its spectrometer SAFARI, will be able to identify and characterize a much larger number of high-z galaxies through these far-IR lines than previously assumed. We discuss the new potentialities offered by SPICA for cosmological studies within this new scenario