{"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/probing-light-relics-through-cosmic-dawn","title":"Probing light relics through cosmic dawn","arxiv_id":"2309.15119","date":"2023-09-26","proceeding":null,"authors":["Nanoom Lee","Selim C. Hotinli"],"abstract":"We explore the prospects of upcoming 21-cm surveys of cosmic dawn ($12\\lesssim \\!z\\lesssim\\!30$) to provide cosmological information on top of upcoming cosmic microwave background (CMB) and large-scale structure surveys, such as CMB-S4, Simons Observatory (SO) and DESI. We focus on the effective number of relativistic species $N_{\\rm eff}$ which is a promising observable for probing beyond the Standard Model theories. We show including upcoming 21-cm surveys such as the Square Kilometre Array (SKA) can allow probing a wide range of models for light particles at $2\\sigma$ level achieving $2\\sigma(N_{\\rm eff})=0.034$ with CMB-S4, for example. Taking into account the degeneracy between $N_{\\rm eff}$ and primordial helium fraction $Y_p$, one can achieve improvements in sensitivities to cosmological parameters, in particular, by more than a factor of 2 for $N_{\\rm eff}$ and dark matter fractional energy density $\\omega_c$.","url_abs":"https://arxiv.org/abs/2309.15119v2","url_pdf":"https://arxiv.org/pdf/2309.15119v2.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":"probing-light-relics-through-cosmic-dawn","repo_url":"https://github.com/lesgourg/class_public","is_official":1,"mentioned_in_paper":1,"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}