We present Keck/HIRES abundance measurements and metal-line kinematic profiles of the damped Lyman alpha systems ( DLAs ) towards the quasars Q0933+733 ( z _ { abs } = 1.479 ) and Q0948+433 ( z _ { abs } = 1.233 ) .
These two DLAs have among the five highest H i column densities at any redshift : N ( HI ) = 4.2 \times 10 ^ { 21 } cm ^ { -2 } .
The metal-line data , presented here for the first time , reveal that these DLAs are noteworthy for several other reasons as well .
1 ) The Q0933+733 DLA exhibits simple kinematic structure with unusually narrow velocity widths as measured from its unsaturated metal lines ( \Delta v = 16 km s ^ { -1 } ) .
At 2.6 % solar , it has the second lowest metallicity at z < 2 .
2 ) The Q0948+433 DLA has among the strongest metal-line transitions of any known DLA .
The saturated Si ii \lambda 1808 line implies a high metallicity ( [ Si/H ] > -1 ) and a significant \alpha -enhancement .
The strong metal lines of this DLA have made possible the detection of Ti ii \lambda 1910 , Co ii \lambda 2012 , and Mg i \lambda 2026 .
3 ) We find that the relative gas-phase abundances of both DLAs follow the general trend seen at high redshift , e.g. , enhanced Zn/Fe and Si/Fe , and sub-solar Mn/Fe , indicating that there is little evolution in the nucleosynthetic patterns of DLAs down to this epoch .
4 ) Their high H i column densities imply that these DLAs dominate the column density-weighted cosmic mean metallicity , \left < Z \right > , of the universe at z < 1.5 .
Using the 15 DLAs with measured metallicities in the redshift interval 0.4 < z < 1.5 , we find \left < Z \right > = -0.89 ^ { +0.40 } _ { -0.33 } , where the uncertainties are 95 % confidence limits .