{"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/the-local-group-l-band-survey-the-first","title":"The Local Group L-Band Survey: The First Measurements of Localized Cold Neutral Medium Properties in the Low-Metallicity Dwarf Galaxy NGC 6822","arxiv_id":"2407.13829","date":"2024-07-18","proceeding":null,"authors":["Nickolas M. Pingel","Hongxing Chen","Snežana Stanimirović","Eric W. Koch","Adam K. Leroy","Erik Rosolowsky","Chang-Goo Kim","Julianne J. Dalcanton","Fabian Walter","Michael P. Busch","Ryan Chown","Jennifer Donovan Meyer","Cosima Eibensteiner","Deidre A. Hunter","Sumit K. Sarbadhicary","Elizabeth Tarantino","Vicente Villanueva","Thomas G. Williams"],"abstract":"Measuring the properties of the cold neutral medium (CNM) in low-metallicity galaxies provides insight into heating and cooling mechanisms in early Universe-like environments. We report detections of two localized atomic neutral hydrogen (HI) absorption features in NGC 6822, a low-metallicity (0.2 Z$_{\\odot}$) dwarf galaxy in the Local Group. These are the first unambiguous CNM detections in a low-metallicity dwarf galaxy outside the Magellanic Clouds. The Local Group L-Band Survey (LGLBS) enabled these detections due to its high spatial (15 pc for HI emission) and spectral (0.4 \\kms) resolution. We introduce LGLBS and describe a custom pipeline to search for HI absorption at high angular resolution and extract associated HI emission. A detailed Gaussian decomposition and radiative transfer analysis of the NGC 6822 detections reveals five CNM components, with key properties: a mean spin temperature of 32$\\pm$6 K, a mean CNM column density of 3.1$\\times$10$^{20}$ cm$^{-2}$, and CNM mass fractions of 0.33 and 0.12 for the two sightlines. Stacking non-detections does not reveal low-level signals below our median optical depth sensitivity of 0.05. One detection intercepts a star-forming region, with the HI absorption profile encompassing the CO (2$-$1) emission, indicating coincident molecular gas and a depression in high-resolution HI emission. We also analyze a nearby sightline with deep, narrow HI self-absorption dips, where the background warm neutral medium is attenuated by intervening CNM. The association of CNM, CO, and H$\\alpha$ emissions suggests a close link between the colder, denser HI phase and star formation in NGC 6822.","url_abs":"https://arxiv.org/abs/2407.13829v1","url_pdf":"https://arxiv.org/pdf/2407.13829v1.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":"the-local-group-l-band-survey-the-first","repo_url":"https://github.com/nipingel/LGLBS_Absorption","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}