The connection between high-redshift galaxies and Lyman α transmission in the Sherwood–Relics simulations of patchy reionization

Conaboy, Luke; Bolton, James S; Keating, Laura C; Haehnelt, Martin G; Kulkarni, Girish; Puchwein, Ewald

Abstract

Recent work has suggested that, during reionization, spatial variations in the ionizing radiation field should produce enhanced Ly α forest transmission at distances of tens of comoving Mpc from high-redshift galaxies. We demonstrate that the Sherwood–Relics suite of hybrid radiation-hydrodynamical simulations are qualitatively consistent with this interpretation. The shape of the galaxy–Ly α transmission cross-correlation is sensitive to both the mass of the haloes hosting the galaxies and the volume averaged fraction of neutral hydrogen in the IGM, x¯H I. The reported excess Ly α forest transmission on scales r ∼ 10 cMpc at z ≈ 5.2 – as measured using C IV absorbers as proxies for high-redshift galaxies – is quantitatively reproduced by Sherwood–Relics at z = 6 if we assume the galaxies that produce ionizing photons are hosted in haloes with mass Mh ≥ 1010 h−1 M. However, this redshift mismatch is equivalent to requiring x¯H I ∼ 0.1 at z 5.2, which is inconsistent with the observed Ly α forest effective optical depth distribution. We suggest this tension may be partly resolved if the minimum C IV absorber host halo mass at z > 5 is larger than Mh = 1010 h−1 M. After reionization completes, relic IGM temperature fluctuations will continue to influence the shape of the cross-correlation on scales of a few comoving Mpc at 4 ≤ z ≤ 5. Constraining the redshift evolution of the cross-correlation over this period may therefore provide further insight into the timing of reionization.

Citation

Conaboy, L., Bolton, J. S., Keating, L. C., Haehnelt, M. G., Kulkarni, G., & Puchwein, E. (2025). The connection between high-redshift galaxies and Lyman α transmission in the Sherwood–Relics simulations of patchy reionization. Monthly Notices of the Royal Astronomical Society, 539(3), 2790–2805. https://doi.org/10.1093/mnras/staf648

• Journal Article Type: Article
• Acceptance Date: Apr 17, 2025
• Online Publication Date: Apr 25, 2025
• Publication Date: 2025-05
• Deposit Date: May 7, 2025
• Publicly Available Date: May 7, 2025
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 539
• Issue: 3
• Pages: 2790–2805
• DOI: https://doi.org/10.1093/mnras/staf648
• Keywords: methods: numerical, galaxies: high-redshift, intergalactic medium, quasars: absorption lines, dark ages, reionization, first stars, large-scale structure of Universe
• Public URL: https://nottingham-repository.worktribe.com/output/48350701
• Publisher URL: https://academic.oup.com/mnras/article/539/3/2790/8120221#513608086