Ca Ii and Dla Absorption Line Systems: Dust, Metals and Star Formation at 0.4 < Z < 1.3

Absorption line studies of galaxies along the line-of-sight to distant quasars allow a direct observational link between the properties of the extended gaseous disk/halo and of the star forming region of galaxies. In these proceedings we review recent work on Ca ii absorbers detected in the SDSS at 0.4 < z < 1.3 which, because of their dust content and chemical properties, may lie spatially closer to the central host galaxy than most DLAs. We present direct evidence for the presence of star formation, through observation of the [O ii] λλ3727,3730 emission line, in both Ca ii absorbers and Mg ii-selected Damped-Lyman-α (DLA) systems. The measured SFR from light falling within the SDSS fibre apertures (corresponding to physical radii of 6 − 9h −1 kpc) is 0.11 − 0.48 M⊙yr −1 for the Ca ii-absorbers and 0.11 − 0.14 M⊙yr −1 for the Mg ii-selected DLAs. The contribution of both Ca ii absorbers and DLAs to the total observed star formation rate density, ˙ ρ * , in the redshift range 0.4 < z < 1.3, is small, < 10%. Our result contrasts with recent conclusions, based on the Schmidt law, that DLA absorbers can account for the majority of the total observed ˙ ρ * in the same redshift range.