Exploring the influence of reionisation-era galaxies on their local intergalactic medium using the Sherwood-Relics simulations
Abstract
Recent surveys have detected excess flux in the Lyman-α forest of quasar spectra several Mpc from high-redshift line-emitting galaxies, indicating a correlation between intergalactic medium (IGM) transmission and reionisation-era galaxies. We examine the galaxy-IGM connection using the Sherwood-Relics simulation suite, a set of hybrid radiation-hydrodynamic simulations that model the IGM at high redshift. We simulate the Lyman-α forest and a population of mock [OIII] emitters using the survey specifications of JWST's ASPIRE programme. We measure the evolution of the effective optical depth in regions close to galaxies, and contrast this with a control sample probing the random IGM. We characterise the changing physical properties of the IGM to explain the observed sightline-to-sightline scatter in opacity between 5.4 < z < 6.2. We find that the IGM is more opaque than average at small radii (r ≤ 5 cMpc/h) close to galaxies, as these regions are overdense. At larger radii (15 < r ≤ 50 cMpc/h), the IGM is more ionised than average, due to the higher photoionisation rate near galaxies. We find qualitative agreement with the observational results from ASPIRE, though we see large realisation-to-realisation scatter driven by cosmic variance, as also seen in theoretical explorations of the galaxy-Lyα transmission cross-correlation function. Our results generally agree with observations claiming that there is a large-scale ionisation bias around [OIII] emitters, supporting the idea that their role is significant in shaping the properties of the IGM during reionisation.
Related
- High Resolution Grid-based Simulations of the Warm-Hot Intergalactic Medium
- A Composite Rest-Frame UV Spectrum of Galaxies at 5.7 < z < 6.9: Ionization, Outflows, and Implications for Intergalactic Metal Enrichment
- First Light and Reionization Epoch Simulations (FLARES) XXII: UV-dust spatial offsets at the Epoch of Reionisation
- First Light and Reionization Epoch Simulations (FLARES) XXII: UV-dust spatial offsets at the Epoch of Reionisation
- Resolving the Assembly of Disk Galaxies from the Epoch of Reionisation to Cosmic Noon
BibTeX
@misc{anderson2026exploring,
title = {{Exploring the influence of reionisation-era galaxies on their local intergalactic medium using the Sherwood-Relics simulations}},
author = {Hamish Anderson and Laura C. Keating and Luke Conaboy and Xiangyu Jin and James S. Bolton and Ewald Puchwein},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.26483},
eprint = {2609.26483},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.26483},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Exploring the influence of reionisation-era galaxies on their local intergalactic medium using the Sherwood-Relics simulations
AU - Hamish Anderson
AU - Laura C. Keating
AU - Luke Conaboy
AU - Xiangyu Jin
AU - James S. Bolton
AU - Ewald Puchwein
PY - 2026
DA - 2026/09/22
PB - arXiv
DO - 10.48550/arxiv.2609.26483
UR - https://arxiv.org/abs/2609.26483
AB - Recent surveys have detected excess flux in the Lyman-α forest of quasar spectra several Mpc from high-redshift line-emitting galaxies, indicating a correlation between intergalactic medium (IGM) transmission and reionisation-era galaxies. We examine the galaxy-IGM connection using the Sherwood-Relics simulation suite, a set of hybrid radiation-hydrodynamic simulations that model the IGM at high redshift. We simulate the Lyman-α forest and a population of mock [OIII] emitters using the survey specifications of JWST's ASPIRE programme. We measure the evolution of the effective optical depth in regions close to galaxies, and contrast this with a control sample probing the random IGM. We characterise the changing physical properties of the IGM to explain the observed sightline-to-sightline scatter in opacity between 5.4 < z < 6.2. We find that the IGM is more opaque than average at small radii (r ≤ 5 cMpc/h) close to galaxies, as these regions are overdense. At larger radii (15 < r ≤ 50 cMpc/h), the IGM is more ionised than average, due to the higher photoionisation rate near galaxies. We find qualitative agreement with the observational results from ASPIRE, though we see large realisation-to-realisation scatter driven by cosmic variance, as also seen in theoretical explorations of the galaxy-Lyα transmission cross-correlation function. Our results generally agree with observations claiming that there is a large-scale ionisation bias around [OIII] emitters, supporting the idea that their role is significant in shaping the properties of the IGM during reionisation.
ER -