The Cosmic Evolution of C <scp>IV</scp> Absorbers at 1.4 &lt; <i>z</i> &lt; 4.5: Insights from 100,000 Systems in DESI Quasars

Abstract We present the largest catalog to date of triply ionized carbon (C iv ) 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 C iv systems in the redshift range 1.4 &lt; z &lt; 4.5 from 300,637 quasar spectra. Completeness is estimated via Monte Carlo simulations, and the catalog is 50% complete at EW C IV ≥ 0.4 Å. 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 C iv , Ω C IV , 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 C IV , we estimate a lower limit on intergalactic medium metallicity <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">IGM</mml:mi> </mml:mrow> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> <mml:mo>≳</mml:mo> <mml:mo>−</mml:mo> <mml:mn>3.25</mml:mn> </mml:math> at z ∼ 2.3, with a smooth decline at higher redshifts. These trends trace the cosmic star formation history and He ii photoheating rate, suggesting a link between C iv 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.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-09-04
DOI
https://doi.org/10.3847/1538-4357/adef3c
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
0.00

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article

The Cosmic Evolution of C IV Absorbers at 1.4 < z < 4.5: Insights from 100,000 Systems in DESI Quasars

Abhijeet Anand, D. Brooks, Rongpu Zhou, A. Muñoz-Gutiérrez et al.
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
article

The Cosmic Evolution of C IV Absorbers at 1.4 < z < 4.5: Insights from 100,000 Systems in DESI Quasars

Abhijeet Anand, D. Brooks, Rongpu Zhou, A. Muñoz-Gutiérrez, S. Juneau, H. K. Herrera-Alcantar, Gregory Tarlé, L. Napolitano, Andreu Font-Ribera, Laurent Le Guillou, David Sprayberry, D. Bianchi, David J. Schlegel, Ignasi Pérez-Ràfols, Axel de la Macorra, B. A. Weaver, Martin Landriau, Matthew J. Temple, Simone Ferraro, A. Brodzeller, M. E. Levi, Marc Manera, J. Aguilar, Anthony Kremin, J. Guy, Eusebio Sanchez, Satya Gontcho A Gontcho, Andrei Cuceu, J. E. Forero-Romero, Steven P. Ahlen, Aaron Meisner, R. Miquel, R. Kehoe, John Moustakas, Mustapha Ishak, Rebecca Canning, Graziano Rossi, P. Doel, G. Gutierrez, M. Schubnell, E. Gaztañaga, T. Claybaugh
article en

Abstract

Abstract We present the largest catalog to date of triply ionized carbon (C iv ) 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 C iv systems in the redshift range 1.4 &lt; z &lt; 4.5 from 300,637 quasar spectra. Completeness is estimated via Monte Carlo simulations, and the catalog is 50% complete at EW C IV ≥ 0.4 Å. 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 C iv , Ω C IV , 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 C IV , we estimate a lower limit on intergalactic medium metallicity <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">IGM</mml:mi> </mml:mrow> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> <mml:mo>≳</mml:mo> <mml:mo>−</mml:mo> <mml:mn>3.25</mml:mn> </mml:math> at z ∼ 2.3, with a smooth decline at higher redshifts. These trends trace the cosmic star formation history and He ii photoheating rate, suggesting a link between C iv 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.

The Astrophysical JournalVol. 990(2)
U.S. Department of Energy
Openalex Percentile: Top 83%
Galaxies: Formation, Evolution, Phenomena
DOIOpen Access PDFOpenAlex
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