{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/quantifying-lyman-a-emissions-from","title":"Quantifying Lyman-$α$ emissions from reionization fronts","arxiv_id":"2406.14622","date":"2024-06-20","proceeding":null,"authors":["Bayu Wilson","Anson D'Aloisio","Christopher Cain","Eli Visbal","George D. Becker"],"abstract":"During reionization, intergalactic ionization fronts (I-fronts) are sources of Ly$\\alpha$ line radiation produced by collisional excitation of hydrogen atoms within the fronts. In principle, detecting this emission could provide direct evidence for a reionizing intergalactic medium (IGM). In this paper, we use a suite of high-resolution one-dimensional radiative transfer simulations run on cosmological density fields to quantify the parameter space of I-front Ly$\\alpha$ emission. We find that the Ly$\\alpha$ production efficiency -- the ratio of emitted Ly$\\alpha$ flux to incident ionizing flux driving the front -- depends mainly on the I-front speed and the spectral index of the ionizing radiation. IGM density fluctuations on scales smaller than the typical I-front width produce scatter in the efficiency, but they do not significantly boost its mean value. The Ly$\\alpha$ flux emitted by an I-front is largest if 3 conditions are met simultaneously: (1) the incident ionizing flux is large; (2) the incident spectrum is hard, consisting of more energetic photons; (3) the I-front is traveling through a cosmological over-density, which causes it to propagate more slowly. We present a convenient parameterization of the efficiency in terms of I-front speed and incident spectral index. We make these results publicly available as an interpolation table and we provide a simple fitting function for a representative ionizing background spectrum. Our results can be applied as a sub-grid model for I-front Ly$\\alpha$ emissions in reionization simulations with spatial and/or temporal resolutions too coarse to resolve I-front structure. In a companion paper, we use our results to explore the possibility of directly imaging Ly$\\alpha$ emission around neutral islands during the last phases of reionization.","url_abs":"https://arxiv.org/abs/2406.14622v2","url_pdf":"https://arxiv.org/pdf/2406.14622v2.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"quantifying-lyman-a-emissions-from","repo_url":"https://github.com/bayu-wilson/1drt_quantify_reion_fronts","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":1,"framework":"none","reach":null},{"paper_slug":"quantifying-lyman-a-emissions-from","repo_url":"https://github.com/bayu-wilson/master_1d_rt","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":1,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}