{"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/neutraluniversemachine-an-empirical-model-for","title":"NeutralUniverseMachine: An Empirical Model for the Evolution of HI and H$_2$ Gas in the Universe","arxiv_id":"2307.07078","date":"2023-07-13","proceeding":null,"authors":["Hong Guo","Jing Wang","Michael G. Jones","Peter Behroozi"],"abstract":"Accurately modeling the cold gas content in the universe is challenging for current theoretical models. We propose a new empirical model NeutralUniverseMachine for the evolution of HI and H$_2$ gas along with dark matter halos based on the UniverseMachine catalog. It is able to accurately describe the observed HI and H$_2$ mass functions, molecular-to-atomic ratio, HI-halo mass relation, HI/H$_2$-stellar mass relations at $z\\sim0$, as well as the evolution of cosmic gas densities $\\rho_{\\rm HI}$ and $\\rho_{\\rm H_2}$ in $0<z<6$. The predictions from our model include: (i) There is weak evolution of HI mass function in $0<z<3$, but the evolution of H$_2$ mass function is much stronger at the massive end. (ii) The average HI and H$_2$ masses at a given stellar mass decrease by around 1 dex since $z=3$ for the star-forming galaxies, but the evolution for the quenched galaxies is much weaker. (iii) Star-forming galaxies have varying HI depletion time $\\tau_{\\rm HI}$ from 0.1 Gyr to 10 Gyr, and the dependence of $\\tau_{\\rm HI}$ on stellar mass and redshift is much stronger than those of H$_2$ depletion time. The quenched galaxies have much longer gas depletion time and weaker redshift evolution. (iv) The cosmic baryon density associated with galaxies is dominated by stars for $z<1.2$ and mainly contributed by HI gas at higher redshifts. (v) The HI bias gradually increases with the redshift from 0.69 to 2.33 in $0<z<3$ and is consistent with recent HI intensity mapping experiments.","url_abs":"https://arxiv.org/abs/2307.07078v2","url_pdf":"https://arxiv.org/pdf/2307.07078v2.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":"neutraluniversemachine-an-empirical-model-for","repo_url":"https://github.com/bulk826r/eden","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"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}