Addressing the $H_0$ tension through matter with pressure and no early dark energy
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arXiv
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| Natura: | Preprint |
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2025
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| author | Carloni, Youri Luongo, Orlando Muccino, Marco |
| author_facet | Carloni, Youri Luongo, Orlando Muccino, Marco |
| contents | We propose that the Hubble tension arises due to an unaccounted additional component, that behaves as \emph{matter with pressure}. We demonstrate that this fluid remains subdominant compared to both dust and radiation throughout nearly the entire universe expansion history. Specifically, the additional fluid satisfies the Zel'dovic limit with a constant equation of state, $ω_s > 0$, and a quite small normalized energy density, $Ω_s$. Accordingly, this component modifies both the sound horizon and the background expansion rate, \emph{acting quite differently from early dark energy models}, without significantly affecting the other cosmological parameters. To show this, we perform a Monte Carlo Markov chain analysis of our model, hereafter dubbed $Λ_{ω_s}$CDM paradigm, using the publicly available \texttt{CLASS} Boltzmann code. Our results confirm the presence of this fluid, with properties that closely resemble those of radiation. We find best-fit values that satisfy $ω_s \lesssim ω_γ$ and a relative energy density $Ω_s / Ω_γ= 0.45$, with $ω_r$ and $Ω_r$ the equation of state and density of photons, respectively. The effective fluid may be associated with generalized K-essence models or, alternatively, with Proca-type vector fields, albeit we do not exclude \emph{a priori} more exotic possibilities, i.e., dark radiation, axions, and so on. Physical implications of our results are analyzed in detail, indicating a statistical preference for the $Λ_{ω_s}$CDM scenario over the conventional $Λ$CDM background. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_11531 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Addressing the $H_0$ tension through matter with pressure and no early dark energy Carloni, Youri Luongo, Orlando Muccino, Marco Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology We propose that the Hubble tension arises due to an unaccounted additional component, that behaves as \emph{matter with pressure}. We demonstrate that this fluid remains subdominant compared to both dust and radiation throughout nearly the entire universe expansion history. Specifically, the additional fluid satisfies the Zel'dovic limit with a constant equation of state, $ω_s > 0$, and a quite small normalized energy density, $Ω_s$. Accordingly, this component modifies both the sound horizon and the background expansion rate, \emph{acting quite differently from early dark energy models}, without significantly affecting the other cosmological parameters. To show this, we perform a Monte Carlo Markov chain analysis of our model, hereafter dubbed $Λ_{ω_s}$CDM paradigm, using the publicly available \texttt{CLASS} Boltzmann code. Our results confirm the presence of this fluid, with properties that closely resemble those of radiation. We find best-fit values that satisfy $ω_s \lesssim ω_γ$ and a relative energy density $Ω_s / Ω_γ= 0.45$, with $ω_r$ and $Ω_r$ the equation of state and density of photons, respectively. The effective fluid may be associated with generalized K-essence models or, alternatively, with Proca-type vector fields, albeit we do not exclude \emph{a priori} more exotic possibilities, i.e., dark radiation, axions, and so on. Physical implications of our results are analyzed in detail, indicating a statistical preference for the $Λ_{ω_s}$CDM scenario over the conventional $Λ$CDM background. |
| title | Addressing the $H_0$ tension through matter with pressure and no early dark energy |
| topic | Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2506.11531 |