{"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/disentangling-the-galactic-and-intergalactic","title":"Disentangling the galactic and intergalactic components in 313 observed Lyman-alpha line profiles between redshift 0 and 5","arxiv_id":"2503.03824","date":"2025-03-05","proceeding":null,"authors":["Siddhartha Gurung-López","Chris Byrohl","Max Gronke","Daniele Spinoso","Alberto Torralba","Alberto Fernández-Soto","Pablo Arnalte-Mur","Vicent J. Martínez"],"abstract":"Lyman-Alpha (Lya) photons emitted in star-forming galaxies undergo complex radiative transfer through the interstellar (ISM), circumgalactic (CGM), and intergalactic medium (IGM), imprinting characteristic signatures on their observed line profiles. We use the open-source package zELDA (redshift Estimator for Line profiles of Distant Lyman-Alpha emitters) to disentangle the galactic and intergalactic contributions in 313 Lya spectra observed with HST/COS and MUSE, spanning 0<z<6. zELDA employs artificial neural networks trained on mock Lya spectra generated with Monte Carlo radiative transfer through thin-shell models and IGM transmission curves from the TNG100 simulation. We find that sources at $z<0.5$ exhibit minimal IGM attenuation, whereas at $z>3$ the IGM significantly suppresses the blue peak of Lya. After correcting for IGM effects, the stacked intrinsic galactic Lya line profiles display remarkably little evolution from $z=0$ to $z=6$. We measure the mean IGM Lya escape fraction, finding $<f^{IGM}_{esc}> > 90\\%$ for z<0.5, decreasing from $\\sim0.85$ at $z=3$ to $\\sim0.55$ at $z=5$. Our measurement of the redshift evolution of the Lya IGM escape fraction agrees with independent constraints on the IGM mean optical depth. After a comparison between our $<f^{IGM}_{esc}>$ estimation and the global Lya escape fraction from the literature, our findings indicate that the IGM might dominate Lya observability at redshift z$\\gtrsim$5.0, after which ISM and CGM effects tend to dominate at lower $z$. Our results demonstrate that zELDA enables robust reconstruction of intrinsic Lya spectra and provides a direct probe of the interplay between galactic outflows and IGM transmission across cosmic time.","url_abs":"https://arxiv.org/abs/2503.03824v1","url_pdf":"https://arxiv.org/pdf/2503.03824v1.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":"disentangling-the-galactic-and-intergalactic","repo_url":"https://github.com/sidgl/zelda_ii","is_official":1,"mentioned_in_paper":0,"mentioned_in_github":0,"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}