2025/04/28 by Anand, Abhijeet, Aguilar, J., Ahlen, S. +39
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2504.20299
We present the largest catalog to date of triply ionized carbon (CIV) absorbers detected in quasar spectra from the Dark Energy Spectroscopic Instrument. Using an automated matched-kernel convolution method with adaptive signal-to-noise thresholds, we identify 101,487 CIV systems in the redshift range 1.4 < z < 4.5 from 300,637 quasar spectra. Completeness is estimated via Monte Carlo simulations and catalog is 50% complete at EWCIV ≥ 0.4 Angstroms. The differential equivalent width frequency distribution declines exponentially and shows weak redshift evolution. The absorber incidence per unit comoving path increases by a factor of 2-5 from z ≈ 4.5 to z ≈ 1.4, with stronger redshift evolution for strong systems. Using column densities derived from the apparent optical depth method, we constrain the cosmic mass density of CIV, ΩCIV, which increases by a factor of ∼ 3.8 from (0.82 ± 0.05) × 10-8 at z ≈ 4.5 to (3.16 ± 0.2) × 10-8 at z ≈ 1.4. From Ω\rm CIV, we estimate a lower limit on intergalactic medium metallicity log(Z\rm IGM/Z\odot) \gtrsim -3.25 at z ∼ 2.3, with a smooth decline at higher redshifts. These trends trace the cosmic star formation history and HeII photoheating rate, suggesting a link between CIV enrichment, star formation, and UV background over ∼ 3 Gyr. The catalog also provides a critical resource for future studies connecting circumgalactic metals to galaxy evolution, especially near cosmic noon.