The connection between high-redshift galaxies and Lyman α transmission in the Sherwood–Relics simulations of patchy reionization
Year: 2025
Type: article
Abstract: ABSTRACT Recent work has suggested that, during reionization, spatial variations in the ionizing radiation field should produce enhanced Ly $\alpha$ 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 $\alpha$ 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, $\bar{x}_{\rm H\,I}$. The reported excess Ly $\alpha$ forest transmission on scales $r \sim 10~{\rm cMpc}$ at $\langle z \rangle \approx 5.2$ – 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 $M_{\rm h}\ge 10^{10}~h^{-1}\, {\rm M}_\odot$. However, this redshift mismatch is equivalent to requiring $\bar{x}_{\rm H\,I}\sim 0.1$ at $z\simeq 5.2$, which is inconsistent with the observed Ly $\alpha$ 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 $M_{\rm h}=10^{10}~h^{-1}\, {\rm M}_\odot$. 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 $4 \le z \le 5$. Constraining the redshift evolution of the cross-correlation over this period may therefore provide further insight into the timing of reionization.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: Department for Business, Energy and Industrial Strategy, UK Government, University of Cambridge, Durham University, Partnership for Advanced Computing in Europe AISBL, Hopkins Population Center, Johns Hopkins University, Science and Technology Facilities Council, H2020 European Research Council
Awards: G1468651527, DiRAC-2.5 - the pathway to DiRAC Phase 3, G2368581224, G2843074508, G3120427512, G3355893731, The DiRAC 2.5x Facility, Consolidated Grant Astronomy Observation and Theory 2019-2022, G4251892262, DiRAC 2.5 Operations 2017-2020, Astronomy Observation and Theory Consolidated Grant 2016-2019, DiRAC 2.5 - the pathway to DiRAC Phase 3, DiRAC-2.5 DC - Operations 2017-2020, DiRAC: Memory Intensive 2.5x, Astronomy and Astrophysics at the University of Nottingham - 2023 to 2026
OpenAlex ID: W4409788430