{"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/constraining-the-dense-matter-equation-of-2","title":"Constraining the dense matter equation of state with new NICER mass-radius measurements and new chiral effective field theory inputs","arxiv_id":"2407.06790","date":"2024-07-09","proceeding":null,"authors":["Nathan Rutherford","Melissa Mendes","Isak Svensson","Achim Schwenk","Anna L. Watts","Kai Hebeler","Jonas Keller","Chanda Prescod-Weinstein","Devarshi Choudhury","Geert Raaijmakers","Tuomo Salmi","Patrick Timmerman","Serena Vinciguerra","Sebastien Guillot","James M. Lattimer"],"abstract":"Pulse profile modeling of X-ray data from NICER is now enabling precision inference of neutron star mass and radius. Combined with nuclear physics constraints from chiral effective field theory ($\\chi$EFT), and masses and tidal deformabilities inferred from gravitational wave detections of binary neutron star mergers, this has lead to a steady improvement in our understanding of the dense matter equation of state (EOS). Here we consider the impact of several new results: the radius measurement for the 1.42$\\,M_\\odot$ pulsar PSR J0437$-$4715 presented by Choudhury et al. (2024), updates to the masses and radii of PSR J0740$+$6620 and PSR J0030$+$0451, and new $\\chi$EFT results for neutron star matter up to 1.5 times nuclear saturation density. Using two different high-density EOS extensions -- a piecewise-polytropic (PP) model and a model based on the speed of sound in a neutron star (CS) -- we find the radius of a 1.4$\\,M_\\odot$ (2.0$\\,M_\\odot$) neutron star to be constrained to the 95% credible ranges $12.28^{+0.50}_{-0.76}\\,$km ($12.33^{+0.70}_{-1.34}\\,$km) for the PP model and $12.01^{+0.56}_{-0.75}\\,$km ($11.55^{+0.94}_{-1.09}\\,$km) for the CS model. The maximum neutron star mass is predicted to be $2.15^{+0.14}_{-0.16}\\,$$M_\\odot$ and $2.08^{+0.28}_{-0.16}\\,$$M_\\odot$ for the PP and CS model, respectively. We explore the sensitivity of our results to different orders and different densities up to which $\\chi$EFT is used, and show how the astrophysical observations provide constraints for the pressure at intermediate densities. Moreover, we investigate the difference $R_{2.0} - R_{1.4}$ of the radius of 2$\\,M_\\odot$ and 1.4$\\,M_\\odot$ neutron stars within our EOS inference.","url_abs":"https://arxiv.org/abs/2407.06790v2","url_pdf":"https://arxiv.org/pdf/2407.06790v2.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":"constraining-the-dense-matter-equation-of-2","repo_url":"https://zenodo.org/record/10871353","is_official":1,"mentioned_in_paper":0,"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}