Model-independent cosmological inference post DESI DR1 BAO measurements
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arXiv
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| Format: | Preprint |
| Publié: |
2024
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| _version_ | 1866908680257011712 |
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| author | Mukherjee, Purba Sen, Anjan Ananda |
| author_facet | Mukherjee, Purba Sen, Anjan Ananda |
| contents | In this work, we implement Gaussian process regression to reconstruct the expansion history of the universe in a model-agnostic manner, using the Pantheon-Plus SN-Ia compilation in combination with two different BAO measurements (SDSS-IV and DESI DR1). In both the reconstructions, the $Λ$CDM model is always included in the 95\% confidence intervals. We find evidence that the DESI LRG data at $z_{\text{eff}} = 0.51$ is not an outlier within our model-independent framework. We study the $\mathcal{O}m$-diagnostics and the evolution of the total equation of state (EoS) of our universe, which hint towards the possibility of a quintessence-like dark energy scenario with a very slowly varying EoS, and a phantom-crossing in higher $z$. The entire exercise is later complemented by considering two more SN-Ia compilations - DES-5YR and Union3 - in combination with DESI BAO. Reconstruction with the DESI BAO + DES-5YR SN data sets predicts that the $Λ$CDM model lies outside the 3$σ$ confidence levels, whereas with DESI BAO + Union3 data, the $Λ$CDM model is always included within 1$σ$. We also report constraints on $H_0 r_d$ from our model-agnostic analysis, independent of the pre-recombination physics. Our results point towards an $\approx$ 2$σ$ discrepancy between the DESI + Pantheon-Plus and DESI + DES-5YR data sets, which calls for further investigation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_19178 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Model-independent cosmological inference post DESI DR1 BAO measurements Mukherjee, Purba Sen, Anjan Ananda Cosmology and Nongalactic Astrophysics Machine Learning General Relativity and Quantum Cosmology In this work, we implement Gaussian process regression to reconstruct the expansion history of the universe in a model-agnostic manner, using the Pantheon-Plus SN-Ia compilation in combination with two different BAO measurements (SDSS-IV and DESI DR1). In both the reconstructions, the $Λ$CDM model is always included in the 95\% confidence intervals. We find evidence that the DESI LRG data at $z_{\text{eff}} = 0.51$ is not an outlier within our model-independent framework. We study the $\mathcal{O}m$-diagnostics and the evolution of the total equation of state (EoS) of our universe, which hint towards the possibility of a quintessence-like dark energy scenario with a very slowly varying EoS, and a phantom-crossing in higher $z$. The entire exercise is later complemented by considering two more SN-Ia compilations - DES-5YR and Union3 - in combination with DESI BAO. Reconstruction with the DESI BAO + DES-5YR SN data sets predicts that the $Λ$CDM model lies outside the 3$σ$ confidence levels, whereas with DESI BAO + Union3 data, the $Λ$CDM model is always included within 1$σ$. We also report constraints on $H_0 r_d$ from our model-agnostic analysis, independent of the pre-recombination physics. Our results point towards an $\approx$ 2$σ$ discrepancy between the DESI + Pantheon-Plus and DESI + DES-5YR data sets, which calls for further investigation. |
| title | Model-independent cosmological inference post DESI DR1 BAO measurements |
| topic | Cosmology and Nongalactic Astrophysics Machine Learning General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2405.19178 |