Constraints on AvERA Cosmologies from Cosmic Chronometers and Type Ia Supernovae
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| Format: | Preprint |
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2025
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| _version_ | 1866918287100608512 |
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| author | Pataki, Adrienn Raffai, Péter Csabai, István Rácz, Gábor Szapudi, István |
| author_facet | Pataki, Adrienn Raffai, Péter Csabai, István Rácz, Gábor Szapudi, István |
| contents | We constrain AvERA cosmologies in comparison with the flat $Λ$CDM model using cosmic chronometer (CC) data and the Pantheon+ sample of type Ia supernovae (SNe Ia). The analysis includes fits to both CC and SN datasets using the \texttt{dynesty} dynamic nested sampling algorithm. For model comparison, we use the Bayesian model evidences and Anderson-Darling tests applied to the normalized residuals to assess consistency with a standard normal distribution. Best-fit parameters are derived within the redshift ranges $z \leq 2$ for CCs and $z \leq 2.3$ for SNe. For the baseline AvERA cosmology, we obtain best-fit values of the Hubble constant of ${H_0=68.32_{-3.27}^{+3.21}~\mathrm{km~s^{-1}~Mpc^{-1}}}$ from the CC analysis and ${H_0=71.99_{-1.03}^{+1.05}~\mathrm{km~s^{-1}~Mpc^{-1}}}$ from the SN analysis, each consistent within $1σ$ with the corresponding AvERA simulation value of $H(z=0)$. While both the CC and SN datasets yield higher Bayesian evidence for the flat $Λ$CDM model, they favor the AvERA cosmologies according to the Anderson-Darling test. We have identified signs of overfitting in each model, which suggests the possibility of overestimating the uncertainties in the Pantheon+ covariance matrix. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_21369 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Constraints on AvERA Cosmologies from Cosmic Chronometers and Type Ia Supernovae Pataki, Adrienn Raffai, Péter Csabai, István Rácz, Gábor Szapudi, István Cosmology and Nongalactic Astrophysics We constrain AvERA cosmologies in comparison with the flat $Λ$CDM model using cosmic chronometer (CC) data and the Pantheon+ sample of type Ia supernovae (SNe Ia). The analysis includes fits to both CC and SN datasets using the \texttt{dynesty} dynamic nested sampling algorithm. For model comparison, we use the Bayesian model evidences and Anderson-Darling tests applied to the normalized residuals to assess consistency with a standard normal distribution. Best-fit parameters are derived within the redshift ranges $z \leq 2$ for CCs and $z \leq 2.3$ for SNe. For the baseline AvERA cosmology, we obtain best-fit values of the Hubble constant of ${H_0=68.32_{-3.27}^{+3.21}~\mathrm{km~s^{-1}~Mpc^{-1}}}$ from the CC analysis and ${H_0=71.99_{-1.03}^{+1.05}~\mathrm{km~s^{-1}~Mpc^{-1}}}$ from the SN analysis, each consistent within $1σ$ with the corresponding AvERA simulation value of $H(z=0)$. While both the CC and SN datasets yield higher Bayesian evidence for the flat $Λ$CDM model, they favor the AvERA cosmologies according to the Anderson-Darling test. We have identified signs of overfitting in each model, which suggests the possibility of overestimating the uncertainties in the Pantheon+ covariance matrix. |
| title | Constraints on AvERA Cosmologies from Cosmic Chronometers and Type Ia Supernovae |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2503.21369 |