Cosmic Chronometers, Pantheon+ Supernovae, and Quasars Favor Coasting Cosmologies over the Flat ΛCDM Model
We test and compare coasting cosmological models with curvature parameters $k=\left\{-1,0,+1\right\}$ in ${H}_{0}^{2}{c}^{-2}$ units and the flat ΛCDM model by fitting them to cosmic chronometers (CCs), the Pantheon+ sample of Type Ia supernovae (SNe), and standardized quasars (QSOs). We used the em...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ada249 |
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| author | Peter Raffai Adrienn Pataki Rebeka L. Böttger Alexandra Karsai Gergely Dálya |
| author_facet | Peter Raffai Adrienn Pataki Rebeka L. Böttger Alexandra Karsai Gergely Dálya |
| author_sort | Peter Raffai |
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| description | We test and compare coasting cosmological models with curvature parameters $k=\left\{-1,0,+1\right\}$ in ${H}_{0}^{2}{c}^{-2}$ units and the flat ΛCDM model by fitting them to cosmic chronometers (CCs), the Pantheon+ sample of Type Ia supernovae (SNe), and standardized quasars (QSOs). We used the emcee code for fitting CC data, a custom Markov Chain Monte Carlo implementation for SNe and QSOs, and Anderson–Darling tests for normality on normalized residuals for model comparison. Best-fit parameters are presented, constrained by data within redshift ranges z ≤ 2 for CCs, z ≤ 2.3 for SNe, and z ≤ 7.54 for QSOs. Coasting models, particularly the flat coasting model, are generally favored over the flat ΛCDM model. The overfitting of the flat ΛCDM model to Pantheon+ SNe and the large intrinsic scatter in QSO data suggest a need to refine error estimates in these data sets. We also highlight the seemingly fine-tuned nature of either the CC data or Ω _m _,0 in the flat ΛCDM model to an H _1 = H _0 coincidence when fitting H ( z ) = H _1 z + H _0 , a natural feature of coasting models. |
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| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-090ccfe045c747c4be285fc875c0cc9e2025-01-17T06:51:32ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0197915110.3847/1538-4357/ada249Cosmic Chronometers, Pantheon+ Supernovae, and Quasars Favor Coasting Cosmologies over the Flat ΛCDM ModelPeter Raffai0https://orcid.org/0000-0001-7576-0141Adrienn Pataki1https://orcid.org/0009-0003-2523-6474Rebeka L. Böttger2https://orcid.org/0000-0001-7015-6551Alexandra Karsai3https://orcid.org/0000-0002-6389-3542Gergely Dálya4https://orcid.org/0000-0003-3258-5763Institute of Physics and Astronomy, ELTE Eötvös Loránd University , 1117 Budapest, Hungary ; peter.raffai@ttk.elte.hu; HUN-REN-ELTE Extragalactic Astrophysics Research Group , 1117 Budapest, HungaryInstitute of Physics and Astronomy, ELTE Eötvös Loránd University , 1117 Budapest, Hungary ; peter.raffai@ttk.elte.huInstitute of Physics and Astronomy, ELTE Eötvös Loránd University , 1117 Budapest, Hungary ; peter.raffai@ttk.elte.huInstitute of Physics and Astronomy, ELTE Eötvös Loránd University , 1117 Budapest, Hungary ; peter.raffai@ttk.elte.huL2IT, Laboratoire des 2 Infinis—Toulouse, Université de Toulouse , CNRS/IN2P3, UPS, F-31062 Toulouse Cedex 9, France; Department of Physics and Astronomy , Universiteit Gent, B-9000 Ghent, BelgiumWe test and compare coasting cosmological models with curvature parameters $k=\left\{-1,0,+1\right\}$ in ${H}_{0}^{2}{c}^{-2}$ units and the flat ΛCDM model by fitting them to cosmic chronometers (CCs), the Pantheon+ sample of Type Ia supernovae (SNe), and standardized quasars (QSOs). We used the emcee code for fitting CC data, a custom Markov Chain Monte Carlo implementation for SNe and QSOs, and Anderson–Darling tests for normality on normalized residuals for model comparison. Best-fit parameters are presented, constrained by data within redshift ranges z ≤ 2 for CCs, z ≤ 2.3 for SNe, and z ≤ 7.54 for QSOs. Coasting models, particularly the flat coasting model, are generally favored over the flat ΛCDM model. The overfitting of the flat ΛCDM model to Pantheon+ SNe and the large intrinsic scatter in QSO data suggest a need to refine error estimates in these data sets. We also highlight the seemingly fine-tuned nature of either the CC data or Ω _m _,0 in the flat ΛCDM model to an H _1 = H _0 coincidence when fitting H ( z ) = H _1 z + H _0 , a natural feature of coasting models.https://doi.org/10.3847/1538-4357/ada249CosmologyCosmological modelsObservational cosmologyCosmological parameters |
| spellingShingle | Peter Raffai Adrienn Pataki Rebeka L. Böttger Alexandra Karsai Gergely Dálya Cosmic Chronometers, Pantheon+ Supernovae, and Quasars Favor Coasting Cosmologies over the Flat ΛCDM Model The Astrophysical Journal Cosmology Cosmological models Observational cosmology Cosmological parameters |
| title | Cosmic Chronometers, Pantheon+ Supernovae, and Quasars Favor Coasting Cosmologies over the Flat ΛCDM Model |
| title_full | Cosmic Chronometers, Pantheon+ Supernovae, and Quasars Favor Coasting Cosmologies over the Flat ΛCDM Model |
| title_fullStr | Cosmic Chronometers, Pantheon+ Supernovae, and Quasars Favor Coasting Cosmologies over the Flat ΛCDM Model |
| title_full_unstemmed | Cosmic Chronometers, Pantheon+ Supernovae, and Quasars Favor Coasting Cosmologies over the Flat ΛCDM Model |
| title_short | Cosmic Chronometers, Pantheon+ Supernovae, and Quasars Favor Coasting Cosmologies over the Flat ΛCDM Model |
| title_sort | cosmic chronometers pantheon supernovae and quasars favor coasting cosmologies over the flat λcdm model |
| topic | Cosmology Cosmological models Observational cosmology Cosmological parameters |
| url | https://doi.org/10.3847/1538-4357/ada249 |
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