A Lower Limit to the Universal Density of Metals at [FORMULA][F]z∼3[/F][/FORMULA

Abstract

Column density distribution functions of C IV with 12.05?log(N)?14.35 and Si IV with 11.70?log(N)?13.93 have been obtained using 81 C IV absorbers and 35 Si IV absorbers redward of the Ly? forest in the lines of sight to seven quasars with 2.518?zem?3.78. These distribution functions have been directly integrated to yield ion densities at z = 3-3.5 of ?C iv = (2.0 ? 0.5) ?10 -->?8 and ?Si iv = (7.0?2.6)?10 -->?9 with H0 = 65 km s-1 Mpc-1 and q -->0=0.02 (1 ? errors). A larger sample of 11 quasar lines of sight was used to measure C II/C IV, Si III/Si IV, and N V/C IV ratios, which suggest that C IV and Si IV are the dominant ionization stages and that corrections to ?Carbon and ?Silicon are no more than a factor of 2. Normalizing the ?-process elements to silicon and the Fe-coproduction elements to carbon gives a density of heavy elements in these forest clouds of ?metals=(3.3?0.8)?10 -->?7 (H -->0=65,q -->0=0.02) . The implications for the amount of star formation and for the ionization of the intergalactic medium prior to z=3 are discussed.