GPAge: a Global Parameterization based on cosmic Age for some unified early-time and late-time solutions to the Hubble tension
Abstract
The over 5σ Hubble tension continues to motivate modifications of the standard Λ-cold-dark-matter (ΛCDM) model. The large number of proposed resolutions for the Hubble tension, broadly divided into early- and late-time solutions, motivates phenomenological parametrizations to constrain the viable solution space. Recently, there is a growing interest in unifying early- and late-time solutions. In this work, we extend the original Parametrization based on cosmic Age (PAge) to cover both the early and late Universe. Specifically, we incorporate the radiation-dominated epoch at the background level and complete the perturbation sector within a unified-dark-fluid framework. The resulting parametrization can accurately reproduce target cosmological models at both the background and perturbation levels. Confronting this global PAge with cosmological observations, we find that it improves the best fit relative to ΛCDM, but does not raise H0 significantly enough to alleviate the Hubble tension. Our parametrizations indicate that varying the early-time matter-like density, even together with a flexible late-time expansion history, is insufficient to resolve the Hubble tension. These results suggest that resolving the Hubble tension requires pre-recombination physics beyond a simple retuning of the matter-like density.
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BibTeX
@misc{ling2026gpage,
title = {{GPAge: a Global Parameterization based on cosmic Age for some unified early-time and late-time solutions to the Hubble tension}},
author = {Jia-Le Ling and Shao-Jiang Wang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.30961},
eprint = {2610.30961},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.30961},
}
RIS
TY - UNPB
TI - GPAge: a Global Parameterization based on cosmic Age for some unified early-time and late-time solutions to the Hubble tension
AU - Jia-Le Ling
AU - Shao-Jiang Wang
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.30961
UR - https://arxiv.org/abs/2610.30961
AB - The over 5σ Hubble tension continues to motivate modifications of the standard Λ-cold-dark-matter (ΛCDM) model. The large number of proposed resolutions for the Hubble tension, broadly divided into early- and late-time solutions, motivates phenomenological parametrizations to constrain the viable solution space. Recently, there is a growing interest in unifying early- and late-time solutions. In this work, we extend the original Parametrization based on cosmic Age (PAge) to cover both the early and late Universe. Specifically, we incorporate the radiation-dominated epoch at the background level and complete the perturbation sector within a unified-dark-fluid framework. The resulting parametrization can accurately reproduce target cosmological models at both the background and perturbation levels. Confronting this global PAge with cosmological observations, we find that it improves the best fit relative to ΛCDM, but does not raise H_0 significantly enough to alleviate the Hubble tension. Our parametrizations indicate that varying the early-time matter-like density, even together with a flexible late-time expansion history, is insufficient to resolve the Hubble tension. These results suggest that resolving the Hubble tension requires pre-recombination physics beyond a simple retuning of the matter-like density.
ER -