Recovering Ionizing Photon Escape and Galaxy Scaling Relations in the LzLCS via Si II and C II Absorption Lines and Mock Spectra from a Radiation-Hydrodynamic Simulation
Abstract
In this work, we use a radiation-hydrodynamic simulation of a single ∼109M⊙ virtual galaxy to study Si II and C II line profiles seen in stacked HST/COS spectra of 58 galaxies from the LzLCS+ sample. We compare stacks across three mass bins (M⋆ ≤ 108M⊙, 108-109M⊙, and M⋆ ≥ 109M⊙) and three stacking methods (mean, median, and weighted average) to a library of 22,500 mock spectra. We investigate whether the simulation can accurately mimic real gas features, reveal clear trends with galaxy properties, and provide indirect estimates of the ionizing escape fraction (fesc). We find reasonable agreement between simulated and observed profiles (χ2 < 1) across all mass regimes. Notably, extracting line properties such as EW and Rf from best-fit mock profiles provides a robust alternative to direct empirical trends, particularly in the low-S/N regime where noise frequently biases results. The simulation-based LIS features, although derived from a single virtual object, exhibit clear correlations with M⋆, SFR, and fesc, mirroring established empirical scaling relations. We find that the best-matching mock spectra predominantly originate from simulation time steps corresponding to peak UV luminosity and intense starburst phases, suggesting that these active periods generate the ISM diversity observed in star-forming galaxies. Finally, simulation-based estimates (fescvirtual) reproduce the observed mass-dependent trends in fesc and are in close agreement with the average fesc of the generated stacks. This simulation-based framework establishes a relevant methodology for interpreting spectroscopic observations, including inferring fesc and characterizing physical scaling relations, in high-redshift galaxies from the Epoch of Reionization.
Related
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BibTeX
@misc{trevino2026recovering,
title = {{Recovering Ionizing Photon Escape and Galaxy Scaling Relations in the LzLCS via Si II and C II Absorption Lines and Mock Spectra from a Radiation-Hydrodynamic Simulation}},
author = {John Trevino and Simon Gazagnes and Danielle A. Berg and Kaelee S. Parker and Valentin Mauerhofer and Jeremy Blaizot and Anne Verhamme and Sophia R. Flury and Anne E. Jaskot and Alberto Saldana-Lopez},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.04324},
eprint = {2609.04324},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.04324},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Recovering Ionizing Photon Escape and Galaxy Scaling Relations in the LzLCS via Si II and C II Absorption Lines and Mock Spectra from a Radiation-Hydrodynamic Simulation
AU - John Trevino
AU - Simon Gazagnes
AU - Danielle A. Berg
AU - Kaelee S. Parker
AU - Valentin Mauerhofer
AU - Jeremy Blaizot
AU - Anne Verhamme
AU - Sophia R. Flury
AU - Anne E. Jaskot
AU - Alberto Saldana-Lopez
PY - 2026
DA - 2026/09/03
PB - arXiv
DO - 10.48550/arxiv.2609.04324
UR - https://arxiv.org/abs/2609.04324
AB - In this work, we use a radiation-hydrodynamic simulation of a single ∼10^9M_⊙ virtual galaxy to study Si II and C II line profiles seen in stacked HST/COS spectra of 58 galaxies from the LzLCS+ sample. We compare stacks across three mass bins (M_⋆ ≤ 10^8M_⊙, 10^8-10^9M_⊙, and M_⋆ ≥ 10^9M_⊙) and three stacking methods (mean, median, and weighted average) to a library of 22,500 mock spectra. We investigate whether the simulation can accurately mimic real gas features, reveal clear trends with galaxy properties, and provide indirect estimates of the ionizing escape fraction (f_esc). We find reasonable agreement between simulated and observed profiles (χ^2 < 1) across all mass regimes. Notably, extracting line properties such as EW and R_f from best-fit mock profiles provides a robust alternative to direct empirical trends, particularly in the low-S/N regime where noise frequently biases results. The simulation-based LIS features, although derived from a single virtual object, exhibit clear correlations with M_⋆, SFR, and f_esc, mirroring established empirical scaling relations. We find that the best-matching mock spectra predominantly originate from simulation time steps corresponding to peak UV luminosity and intense starburst phases, suggesting that these active periods generate the ISM diversity observed in star-forming galaxies. Finally, simulation-based estimates (f_esc^virtual) reproduce the observed mass-dependent trends in f_esc and are in close agreement with the average f_esc of the generated stacks. This simulation-based framework establishes a relevant methodology for interpreting spectroscopic observations, including inferring f_esc and characterizing physical scaling relations, in high-redshift galaxies from the Epoch of Reionization.
ER -