{"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/discovery-of-diffuse-optical-emission-lines","title":"Discovery of diffuse optical emission lines from the inner Galaxy: Evidence for LI(N)ER-like gas","arxiv_id":"2007.01872","date":"2020-07-03","proceeding":null,"authors":["Dhanesh Krishnarao","Robert A. Benjamin","L. Matthew Haffner"],"abstract":"Optical emission lines are used to categorize galaxies into three groups according to their dominant central radiation source: active galactic nuclei, star formation, or low-ionization (nuclear) emission regions [LI(N)ERs] that may trace ionizing radiation from older stellar populations. Using the Wisconsin H-Alpha Mapper, we detect optical line emission in low-extinction windows within eight degrees of Galactic Center. The emission is associated with the 1.5-kiloparsec-radius \"Tilted Disk\" of neutral gas. We modify a model of this disk and find that the hydrogen gas observed is at least $48\\%$ ionized. The ratio [NII] $\\lambda$6584 $\\overset{\\lower.5em\\circ}{\\mathrm{A}}$/H$\\alpha$ $\\lambda$6563 $\\overset{\\lower.5em\\circ}{\\mathrm{A}}$ increases from 0.3 to 2.5 with Galactocentric radius; [OIII] $\\lambda$5007 $\\overset{\\lower.5em\\circ}{\\mathrm{A}}$ and H$\\beta$ $\\lambda$4861 $\\overset{\\lower.5em\\circ}{\\mathrm{A}}$ are also sometimes detected. The line ratios for most Tilted Disk sightlines are characteristic of LI(N)ER galaxies.","url_abs":"https://arxiv.org/abs/2007.01872v1","url_pdf":"https://arxiv.org/pdf/2007.01872v1.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":"discovery-of-diffuse-optical-emission-lines","repo_url":"https://github.com/Deech08/modspectra","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":0,"framework":"none","reach":null},{"paper_slug":"discovery-of-diffuse-optical-emission-lines","repo_url":"https://github.com/Deech08/mw_bpt","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":0,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}