High Redshift Metals I.: The Decline of C IV at z > 5.3

Abstract

We present the results from our search for C IV in the intergalactic medium at redshifts z=5.3-6.0. We have observed four z~6 QSOs with Keck/NIRSPEC in echelle mode. The data are the most sensitive yet taken to search for C IV at these redshifts, being 50% complete at column densities log(N_{CIV})=13.4. We find no C IV systems in any of the four sightlines. Taking into account our completeness, this translates into a decline in the number density of C IV absorbers in the range 13.0 < log(N_{CIV}) < 15.0 of at least a factor 4.4 (95% confidence) from z~2-4.5, where the number density is relatively constant. We use our lack of detections to set limits on the slope and normalization of the column density distribution at z=5.3-6.0. The rapid evolution of C IV at these redshifts suggests that the decrease in the number density may largely be due to ionization effects, in which case many of the metals in the z~4.5 IGM could already be in place at z~5.3, but in a lower ionization state. The lack of weak systems in our data, combined with the presence of strong C IV absorbers along at least one other sightline, further suggests that there may be large-scale variations in the enrichment and/or ionization state of the z~6 IGM, or that C IV absorbers at these redshifts are associated with rare, UV-bright star-forming galaxies.

11 pages, 8 figures, submitted to ApJ

References in corpus (15)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• Cosmological Simulations of Intergalactic Medium Enrichment from Galactic Outflows
• Mass, Metal, and Energy Feedback in Cosmological Simulations
• The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field
• HeII Reionization and its Effect on the IGM
• The Evolution of Optical Depth in the Ly-alpha Forest: Evidence Against Reionization at z~6
• The Stellar Masses and Star Formation Histories of Galaxies at z ~ 6: Constraints from Spitzer Observations in the Great Observatories Origins Deep Survey
• The Stellar Mass Density at z~6 from Spitzer Imaging of i-drop Galaxies
• Luminosity Functions of Lyman Alpha Emitting Galaxies and Cosmic Reionization of Hydrogen
• The Environments of High Redshift QSOs
• Intergalactic CIV absorption at redshifts 5.4 to 6
• The Quasar-frame Velocity Distribution of Narrow CIV Absorbers
• High Redshift Intergalactic C IV Abundance Measurements from the Near-Infrared Spectra of Two z~6 QSOs
• He II absorption and the sawtooth spectrum of the cosmic far-UV background

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