Resolving the S8 tension with the Lambda Prime ($Λ'$) model
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2025
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| author | Marongwe, Stuart Kauffman, Stuart Tshipa, Moletlanyi Corda, Christian |
| author_facet | Marongwe, Stuart Kauffman, Stuart Tshipa, Moletlanyi Corda, Christian |
| contents | The $S_8$ parameter, which quantifies the amplitude of matter fluctuations on scales of $8h^{-1}$ Mpc, has been a source of tension between weak lensing surveys (e.g. KiDS, DES, HSC) and the Planck Cosmic Microwave Background (CMB) measurements. This discrepancy challenges the standard $Λ$CDM model and has become one of the most significant tensions in modern cosmology. The ${Λ'}$ model offers a potential resolution by introducing modifications to the cosmic growth history through alterations to the gravitational sector. The alterations involve including a Ricci soliton into Einstein's field equations which introduce a time dependent factor yielding a time varying cosmological constant ${Λ'}=(1-{α(t)^2}{Λ_{DE}}\frac{ρ_g}{ρ_{DE}}$ and subsequently the evolution of the cosmos. The Ricci soliton is sourced from gravitational energy density. In this study we analyze results from six surveys and compare the results for $w_a$ and $w_0$ with the ${Λ'}$ model. We also find $σ_8={0.750}_{-0.020}^{+0.020}$ , $S_8={0.788}$. These values are closer to some low $S_8$ measurements from weak lensing surveys (e.g DES, KiDS), which report $S_8 \approx 0.76-0.78$, suggesting that the model may alleviate the $S_8$ tension. High values of ${α(t)}$ in the late universe are the cause of suppressed structure formation and low values of ${Λ'}$. The late universe in the ${Λ'}$ model is effectively or apparently 5-10% younger than in $Λ$CDM which translates to $H_0={72.734}_{-1.687}^{+1.687}$ km/s/Mpc, which is in agreement with late universe probes. ${Λ'}$ is classified under the dynamical dark energy models, however unlike alternatives, it does not invoke exotic particles nor phantom energy. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_14609 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Resolving the S8 tension with the Lambda Prime ($Λ'$) model Marongwe, Stuart Kauffman, Stuart Tshipa, Moletlanyi Corda, Christian Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology The $S_8$ parameter, which quantifies the amplitude of matter fluctuations on scales of $8h^{-1}$ Mpc, has been a source of tension between weak lensing surveys (e.g. KiDS, DES, HSC) and the Planck Cosmic Microwave Background (CMB) measurements. This discrepancy challenges the standard $Λ$CDM model and has become one of the most significant tensions in modern cosmology. The ${Λ'}$ model offers a potential resolution by introducing modifications to the cosmic growth history through alterations to the gravitational sector. The alterations involve including a Ricci soliton into Einstein's field equations which introduce a time dependent factor yielding a time varying cosmological constant ${Λ'}=(1-{α(t)^2}{Λ_{DE}}\frac{ρ_g}{ρ_{DE}}$ and subsequently the evolution of the cosmos. The Ricci soliton is sourced from gravitational energy density. In this study we analyze results from six surveys and compare the results for $w_a$ and $w_0$ with the ${Λ'}$ model. We also find $σ_8={0.750}_{-0.020}^{+0.020}$ , $S_8={0.788}$. These values are closer to some low $S_8$ measurements from weak lensing surveys (e.g DES, KiDS), which report $S_8 \approx 0.76-0.78$, suggesting that the model may alleviate the $S_8$ tension. High values of ${α(t)}$ in the late universe are the cause of suppressed structure formation and low values of ${Λ'}$. The late universe in the ${Λ'}$ model is effectively or apparently 5-10% younger than in $Λ$CDM which translates to $H_0={72.734}_{-1.687}^{+1.687}$ km/s/Mpc, which is in agreement with late universe probes. ${Λ'}$ is classified under the dynamical dark energy models, however unlike alternatives, it does not invoke exotic particles nor phantom energy. |
| title | Resolving the S8 tension with the Lambda Prime ($Λ'$) model |
| topic | Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2504.14609 |