Systematic Bias in Ionizing Radiation Escape Fraction Measurements from Foreground Large-scale Structures

Claudia M. Scarlata; Wanjia Hu; Matthew J. Hayes; S. Taamoli; Ali A. Khostovan; C. M. Casey; Andreas L. Faisst; Jeyhan S. Kartaltepe; Yu-Heng Lin; Mara Salvato; Marc Rafelski

doi:10.3847/1538-4357/adcf9a

The Astrophysical Journal (Jan 2025)

Systematic Bias in Ionizing Radiation Escape Fraction Measurements from Foreground Large-scale Structures

Claudia M. Scarlata,
Wanjia Hu,
Matthew J. Hayes,
S. Taamoli,
Ali A. Khostovan,
C. M. Casey,
Andreas L. Faisst,
Jeyhan S. Kartaltepe,
Yu-Heng Lin,
Mara Salvato,
Marc Rafelski

Affiliations

Claudia M. Scarlata: ORCiD; Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota , 316 Church Street SE, Minneapolis, MN 55455, USA
Wanjia Hu: Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota , 316 Church Street SE, Minneapolis, MN 55455, USA
Matthew J. Hayes: ORCiD; Stockholm University , Department of Astronomy and Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, SE-10691, Stockholm, Sweden
S. Taamoli: ORCiD; Physics and Astronomy Department, University of California Riverside , USA
Ali A. Khostovan: ORCiD; Department of Physics and Astronomy, University of Kentucky , 505 Rose Street, Lexington, KY 40506, USA
C. M. Casey: ORCiD; Department of Physics, University of California , Santa Barbara, CA 93106, USA; Department of Astronomy, the University of Texas at Austin , 2515 Speedway Blvd Stop C1400, Austin, TX 78712, USA; Cosmic DAWN Center , Denmark
Andreas L. Faisst: ORCiD; Caltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USA
Jeyhan S. Kartaltepe: ORCiD; Laboratory for Multiwavelength Astrophysics, School of Physics and Astronomy, Rochester Institute of Technology , 84 Lomb Memorial Drive, Rochester, NY 14623, USA
Yu-Heng Lin: ORCiD; Caltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USA
Mara Salvato: ORCiD; Max-Planck Institute for Extraterrestrial Physics , Giessenbachstrasse1, 85748, Garching, Germany
Marc Rafelski: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; Department of Physics and Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA

DOI: https://doi.org/10.3847/1538-4357/adcf9a
Journal volume & issue: Vol. 985, no. 1
p. 115

Abstract

Read online

We investigate the relationship between the Ly α forest transmission in the intergalactic medium (IGM) and the environmental density of galaxies, focusing on its implications for the measurement of ionizing radiation escape fractions. Using a sample of 268 spectroscopically confirmed background galaxies at 2.7 < z < 3.0 and a galaxy density map at z ≈ 2.5 within the COSMOS field, we measure the Ly α transmission photometrically, leveraging the multiwavelength data available from the COSMOS2020 catalog. Our results reveal a weak but statistically significant positive correlation between Ly α optical depth and galaxy density contrast, suggesting that overdense regions are enriched in neutral gas, which could bias escape fraction measurements. This emphasizes the need to account for the large-scale structure of the IGM in analyses of ionizing radiation escape fractions and highlights the advantages of a photometric approach for increasing the number of sampled lines of sight across large fields. The photometric redshifts provided by upcoming all-sky surveys, such as Euclid, will make it possible to account for this bias, which can also be minimized by using fields separated in the sky by many degrees.

Intergalactic medium

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

About the journal

Abstract

Keywords