Identifying Cosmological Parameter Anomalies in the Low-Redshift Subset of the Pantheon Dataset: A Comparison between Chi-Square and Bayesian MCMC Methods

Identifying Cosmological Parameter Anomalies in the Low-Redshift Subset of the Pantheon Dataset: A Comparison between Chi-Square and Bayesian MCMC Methods | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Method Article Identifying Cosmological Parameter Anomalies in the Low-Redshift Subset of the Pantheon Dataset: A Comparison between Chi-Square and Bayesian MCMC Methods Michael Japtharican, Rama Dona This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8531151/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This work investigates the possibility of cosmological parameter anomalies in the lowredshift subset of the Pantheon+ compilation (z ≤ 0.03639). Using the Pantheon+SH0ES dataset and its covariance matrix, cosmological parameters (H 0 , Ω m , and ΩΛ) are estimated under the assumption of near-flat curvature (k ≈ 0). The χ 2 and Bayesian MCMC methods are employed to test the robustness of the identified anomaly. The χ 2 method yields narrower uncertainties with broader parameter distributions, while the Bayesian MCMC approach produces smoother distributions with significantly wider uncertainties. These results indicate robust inconsistencies in the low-redshift subset across both methods, suggesting the need to re-evaluate the contribution of low-redshift data to the Hubble tension problem. Astrophysics and Cosmology Astronomy Applied Statistics Type Ia Supernovae Low-Redshift Cosmology Cosmological Parameter Estimation Statistical Methods Full Text Additional Declarations The authors declare no competing interests. Supplementary Files SupplementaryCodeChiSquareMCMC.zip.zip Supplementary Code for Chi-Square and Bayesian MCMC Analysis Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8531151","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Method Article","associatedPublications":[],"authors":[{"id":570189864,"identity":"3de5297a-b071-4b68-8423-1a8cf63d5a8b","order_by":0,"name":"Michael Japtharican","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEklEQVRIie3PMUvDQBTA8SuF63Lq+iSQfILCK4VUl3wM5yuFZkmxk0YEjcv5ITL4FSxCcLwQMEvcBZeI0DldOoqXo4vFJKvg/afj8X48jhCT6U8mCelFhFD17FUh2HpWdpF0R/pQnIz1jHcdqonuQIRT/W4jw7ts/bl59s4PB9m6BAr+w1n2oa549jD6nbjyZYJpMTsVbD7BJYPF6n2OiszGrmwi0oVU9JECcUG1WMW8JnKaNJJ8q8itIoMtMAR/FPtVBynqK5kizAXGgTtW0HWluMRXkSNlwYUFEkaPVrCUHFv+8pYn5ZW4Ruc+T443XzeOE/tPVRV6dhMhIOnPAepNbFivO4r2iBO1bJtMJtO/7BtKNGR18himdwAAAABJRU5ErkJggg==","orcid":"","institution":"SMA Santo Yosef Pangkalpinang","correspondingAuthor":true,"prefix":"","firstName":"Michael","middleName":"","lastName":"Japtharican","suffix":""},{"id":570189865,"identity":"4b513678-66fc-4b71-91ab-e91adcb43a2d","order_by":1,"name":"Rama Dona","email":"","orcid":"","institution":"SMA Santo Yosef Pangkalpinang","correspondingAuthor":false,"prefix":"","firstName":"Rama","middleName":"","lastName":"Dona","suffix":""}],"badges":[],"createdAt":"2026-01-06 12:09:22","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-8531151/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8531151/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":99701400,"identity":"6ab4af38-ce93-467a-a560-fb03958558b3","added_by":"auto","created_at":"2026-01-07 11:46:24","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":353845,"visible":true,"origin":"","legend":"","description":"","filename":"Art1Pantheon.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8531151/v1_covered_1d049653-1930-4f67-b7ae-247bcf8cbb16.pdf"},{"id":99701399,"identity":"7aa62e11-6492-4de0-bba1-e3cadaa9ab11","added_by":"auto","created_at":"2026-01-07 11:46:19","extension":"zip","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1062038,"visible":true,"origin":"","legend":"\u003cp\u003eSupplementary Code for Chi-Square and Bayesian MCMC Analysis\u003c/p\u003e","description":"","filename":"SupplementaryCodeChiSquareMCMC.zip.zip","url":"https://assets-eu.researchsquare.com/files/rs-8531151/v1/3ce31f60f140484fd2fa53ad.zip"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eIdentifying Cosmological Parameter Anomalies in the Low-Redshift Subset of the Pantheon Dataset: A Comparison between Chi-Square and Bayesian MCMC Methods\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"SMA Santo Yosef Pangkalpinang","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Type Ia Supernovae, Low-Redshift Cosmology, Cosmological Parameter Estimation, Statistical Methods","lastPublishedDoi":"10.21203/rs.3.rs-8531151/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8531151/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis work investigates the possibility of cosmological parameter anomalies in the lowredshift subset of the Pantheon+ compilation (z ≤ 0.03639). Using the Pantheon+SH0ES dataset and its covariance matrix, cosmological parameters (H\u003csub\u003e0\u003c/sub\u003e, Ω\u003csub\u003em\u003c/sub\u003e, and ΩΛ) are estimated under the assumption of near-flat curvature (k ≈ 0). The χ\u003csup\u003e2\u003c/sup\u003e and Bayesian MCMC methods are employed to test the robustness of the identified anomaly. The χ\u003csup\u003e2\u003c/sup\u003e method yields narrower uncertainties with broader parameter distributions, while the Bayesian MCMC approach produces smoother distributions with significantly wider uncertainties. These results indicate robust inconsistencies in the low-redshift subset across both methods, suggesting the need to re-evaluate the contribution of low-redshift data to the Hubble tension problem.\u003c/p\u003e","manuscriptTitle":"Identifying Cosmological Parameter Anomalies in the Low-Redshift Subset of the Pantheon Dataset: A Comparison between Chi-Square and Bayesian MCMC Methods","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-07 11:46:14","doi":"10.21203/rs.3.rs-8531151/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"fc787144-daa3-4209-b739-3675a9e540f0","owner":[],"postedDate":"January 7th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":60671650,"name":"Astrophysics and Cosmology"},{"id":60671651,"name":"Astronomy"},{"id":60671652,"name":"Applied Statistics"}],"tags":[],"updatedAt":"2026-01-07T11:46:14+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-07 11:46:14","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8531151","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8531151","identity":"rs-8531151","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}