Tracing the Evolution of $Ω_m(z)$ over the Last 10 Billion Years with Non-parametric Methods
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| Format: | Preprint |
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2026
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| author | Holanda, R. F. L. Jesus, J. F. Santana, Z. C. Nunes, R. C. |
| author_facet | Holanda, R. F. L. Jesus, J. F. Santana, Z. C. Nunes, R. C. |
| contents | We investigate the redshift evolution of the matter density parameter, $Ω_m(z)$, using galaxy cluster gas mass fraction measurements combined with cosmic chronometer $H(z)$ data and type Ia supernova luminosity distances. Our approach employs Gaussian Process Regression to reconstruct $Ω_m(z)$ in a non-parametric way, remaining only weakly dependent on a specific background cosmology. The reconstructed evolution is consistent with the standard $ρ_m \propto (1+z)^3$ scaling predicted by the $Λ$CDM model. We obtain $Ω_{m0}=0.296 \pm 0.044$ from the 44-cluster sample, and $Ω_{m0}=0.271 \pm 0.016$, $0.253 \pm 0.017$, and $0.210 \pm 0.013$ for the 103-cluster compilation, depending on the assumed mass calibration. While $Ω_m(z)$ follows the expected redshift behaviour, the inferred value of $Ω_{m0}$ shows a strong dependence on the cluster mass calibration. Within this framework, mass bias emerges as the dominant source of uncertainty, exceeding statistical errors. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2603_25851 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Tracing the Evolution of $Ω_m(z)$ over the Last 10 Billion Years with Non-parametric Methods Holanda, R. F. L. Jesus, J. F. Santana, Z. C. Nunes, R. C. Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology We investigate the redshift evolution of the matter density parameter, $Ω_m(z)$, using galaxy cluster gas mass fraction measurements combined with cosmic chronometer $H(z)$ data and type Ia supernova luminosity distances. Our approach employs Gaussian Process Regression to reconstruct $Ω_m(z)$ in a non-parametric way, remaining only weakly dependent on a specific background cosmology. The reconstructed evolution is consistent with the standard $ρ_m \propto (1+z)^3$ scaling predicted by the $Λ$CDM model. We obtain $Ω_{m0}=0.296 \pm 0.044$ from the 44-cluster sample, and $Ω_{m0}=0.271 \pm 0.016$, $0.253 \pm 0.017$, and $0.210 \pm 0.013$ for the 103-cluster compilation, depending on the assumed mass calibration. While $Ω_m(z)$ follows the expected redshift behaviour, the inferred value of $Ω_{m0}$ shows a strong dependence on the cluster mass calibration. Within this framework, mass bias emerges as the dominant source of uncertainty, exceeding statistical errors. |
| title | Tracing the Evolution of $Ω_m(z)$ over the Last 10 Billion Years with Non-parametric Methods |
| topic | Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2603.25851 |