{"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-impact-of-weak-lensing-on-type-ia","title":"The impact of weak lensing on Type Ia supernovae luminosity distances","arxiv_id":"2210.10688","date":"2022-10-19","proceeding":null,"authors":["Paul Shah","Pablo Lemos","Ofer Lahav"],"abstract":"When Type Ia supernovae are used to infer cosmological parameters, their luminosities are compared to those from a homogeneous cosmology. In this note we propose a test to examine to what degree SN Ia have been observed on lines of sight where the average matter density is \\textit{not} representative of the homogeneous background. We apply our test to the Pantheon SN Ia compilation, and find two redshift bins which indicate a moderate bias to over-density at $\\sim 2\\sigma$. We modify the Tripp estimator to explicitly de-lens SN Ia magnitudes, and show that this reduces scatter of Hubble diagram residuals. Using our revised Tripp estimator, the effect on cosmological parameters from Pantheon in $\\Lambda$CDM is however small with a change in mean value from $\\Omega_{\\rm m} = 0.317 \\pm 0.027$ (baseline) to $\\Omega_{\\rm m} = 0.312 \\pm 0.025$ (de-lensed). For the Flat $w$CDM case it is $\\Omega_{\\rm m} = 0.332 \\pm 0.049$ and $w = -1.16 \\pm 0.16$ (baseline) versus $\\Omega_{\\rm m} = 0.316 \\pm 0.048$ and $w = -1.12 \\pm 0.15$ (de-lensed). We note that the effect of lensing on cosmological parameters may be larger for future high-z surveys.","url_abs":"https://arxiv.org/abs/2210.10688v2","url_pdf":"https://arxiv.org/pdf/2210.10688v2.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-impact-of-weak-lensing-on-type-ia","repo_url":"https://github.com/paulshah/snlensing","is_official":1,"mentioned_in_paper":1,"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}