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Date and Time of the Query: 2019-07-20 T21:09:54 PDT
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For refcode 2013ApJ...763...37C:
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2013ApJ...763...37C Precious Metals in SDSS Quasar Spectra. I. Tracking the Evolution of Strong, 1.5 < z < 4.5 C IV Absorbers with Thousands of Systems Cooksey, Kathy L.; Kao, Melodie M.; Simcoe, Robert A.; O'Meara, John M.; Prochaska, J. Xavier Abstract. We have vastly increased the C IV statistics at intermediate redshift by surveying the thousands of quasars in the Sloan Digital Sky Survey (SDSS) Data-Release 7. We visually verified over 16,000 C IV systems with 1.46 < z < 4.55---a sample size that renders Poisson error negligible. Detailed Monte Carlo simulations show that we are approximately 50% complete down to rest equivalent widths W_r_ ~ 0.6 A. We analyzed the sample as a whole and in 10 small redshift bins with approximately 1500 doublets each. The equivalent width frequency distributions f(W_r_) were well modeled by an exponential, with little evolution in shape. In contrast with previous studies that modeled the frequency distribution as a single power law, the fitted exponential gives a finite mass density for the C IV ions. The comoving line density d {N}_{{C\,\scriptsize{IV}_}}/dX evolved smoothly with redshift, increasing by a factor of 2.37 +/- 0.09 from z = 4.55-1.96, then plateauing at d {N}_{{C\,\scriptsize{IV}_}}/dX~ 0.34 for z = 1.96-1.46. Comparing our SDSS sample with z < 1 (ultraviolet) and z > 5 (infrared) surveys, we see an approximately 10-fold increase in d {N}_{{C\,\scriptsize{IV}_}}/dX over z ~ 6 --> 0, for W_r_ >= 0.6 A. This suggests a monotonic and significant increase in the enrichment of gas outside galaxies over the 12 Gyr lifetime of the universe. Key words: galaxies: halos, intergalactic medium, quasars: absorption lines, techniques: spectroscopic
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