Consistently Reproducing Early Galaxy Observations and 21-cm Signal during the Epoch of Reionization
Abstract
In the standard cosmological model, galaxies forming within dark matter haloes are the primary drivers of the Epoch of Reionization (EoR). The complex physics of galaxy formation introduces scatter in the relation between halo mass and star-formation activity, with implications for the production and escape of ionising photons. In this work, we implement a stochastic source model in our cosmological radiative transfer simulations. We calibrate our model against the high-redshift ultraviolet luminosity function observed by JWST and observational constraints on Lyman-continuum leakage to constrain the ionising escape fraction. We find that stochastic star formation redistributes ionising emissivity toward lower-mass haloes, producing a more fragmented ionisation topology and delaying the growth of the largest ionised regions relative to the deterministic, observationally calibrated model. However, when the two models match total ionising photon production, their global neutral fractions and 21-cm power spectrum remain nearly indistinguishable, despite small differences in the morphology of individual ionised regions. Additionally, we establish a unified framework that lets us apply source models derived from computationally expensive hydrodynamical simulations (SPICE, FIRE-2 and Thesan) and investigate their impact on large-volume reionisation simulations, extending their prescriptions to scales of >100 Mpc. We find that these prescriptions produce distinct ionisation topologies and 21-cm statistical signatures, even when their global reionisation histories are similar. Our results highlight the importance of combining physically motivated galaxy formation prescriptions from hydrodynamical simulations with large-volume radiative transfer simulations to interpret forthcoming 21-cm observations and constrain the sources of cosmic reionisation.
Related
- Galaxy-to-galaxy stochasticity has a limited impact on reionization and the 21-cm signal at fixed mean emissivity
- Calibration requirements for Epoch of Reionization 21-cm signal observations - V. Bias and variance in the cylindrical power spectrum from uGMRT Band 3 observations of the ELAIS-N1 field
- An ultra-faint, chemically primitive galaxy forming in the reionization era
- Successfully Reproducing Solar Orbiter Polar Field Observations with a Surface Flux Transport Model
- Galaxy protoclusters as drivers of cosmic reionization. II. Te-based metallicities of Lyman-α emitters
BibTeX
@misc{bianco2026consistently,
title = {{Consistently Reproducing Early Galaxy Observations and 21-cm Signal during the Epoch of Reionization}},
author = {Michele Bianco and Sambit K. Giri and Arghyadeep Basu and Tommaso Boschi and Aurel Schneider and Enrico Garaldi and Garrelt Mellema},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.24064},
eprint = {2610.24064},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.24064},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Consistently Reproducing Early Galaxy Observations and 21-cm Signal during the Epoch of Reionization
AU - Michele Bianco
AU - Sambit K. Giri
AU - Arghyadeep Basu
AU - Tommaso Boschi
AU - Aurel Schneider
AU - Enrico Garaldi
AU - Garrelt Mellema
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.24064
UR - https://arxiv.org/abs/2610.24064
AB - In the standard cosmological model, galaxies forming within dark matter haloes are the primary drivers of the Epoch of Reionization (EoR). The complex physics of galaxy formation introduces scatter in the relation between halo mass and star-formation activity, with implications for the production and escape of ionising photons. In this work, we implement a stochastic source model in our cosmological radiative transfer simulations. We calibrate our model against the high-redshift ultraviolet luminosity function observed by JWST and observational constraints on Lyman-continuum leakage to constrain the ionising escape fraction. We find that stochastic star formation redistributes ionising emissivity toward lower-mass haloes, producing a more fragmented ionisation topology and delaying the growth of the largest ionised regions relative to the deterministic, observationally calibrated model. However, when the two models match total ionising photon production, their global neutral fractions and 21-cm power spectrum remain nearly indistinguishable, despite small differences in the morphology of individual ionised regions. Additionally, we establish a unified framework that lets us apply source models derived from computationally expensive hydrodynamical simulations (SPICE, FIRE-2 and Thesan) and investigate their impact on large-volume reionisation simulations, extending their prescriptions to scales of >100 Mpc. We find that these prescriptions produce distinct ionisation topologies and 21-cm statistical signatures, even when their global reionisation histories are similar. Our results highlight the importance of combining physically motivated galaxy formation prescriptions from hydrodynamical simulations with large-volume radiative transfer simulations to interpret forthcoming 21-cm observations and constrain the sources of cosmic reionisation.
ER -