Can cosmic voids ease the Hubble tension? Local expansion in w0waCDM
Abstract
We investigate the effect of local cosmic voids on low-redshift measurements of the Hubble rate in flat w0waCDM cosmologies. Using a hydrodynamical model for isolated spherical inverse top-hat underdensities, we compute the void-induced Hubble shift as a function of redshift, enclosed density contrast δE and cosmological parameters. We find that the effect is mainly controlled by the matter sector, through δE and Ωm,0, while dynamical dark energy gives only subdominant late-time corrections. For a Planck-calibrated ΛCDM background, matching the SH0ES value requires a present-day void with δE(z=0)≃ −0.44, substantially deeper than the KBC-like local underdensity. A KBC-like void lowers the SH0ES-Planck discrepancy to about 2σ, but is not deep enough to fully reconcile the two measurements. Allowing for dynamical dark energy, including regions motivated by recent DES and DESI analyses, changes this result only at the percent level. We also show that the reported redshift dependence of locally inferred H0 values can be represented phenomenologically by an effective enclosed matter profile. This reconstruction should be interpreted as a consistency test of local-structure effects rather than as explanation for an evolving background value of H0. Overall, local underdensities can affect low-redshift Hubble-rate inferences, but they do not resolve the Hubble tension within the spherical void setup considered here.
Versions
Related
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BibTeX
@misc{moretti2026cosmic,
title = {{Can cosmic voids ease the Hubble tension? Local expansion in $w_0w_a$CDM}},
author = {Tommaso Moretti and Noemi Frusciante and Giovanni Verza},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2607.20257},
eprint = {2607.20257},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.20257},
}
RIS
TY - UNPB
TI - Can cosmic voids ease the Hubble tension? Local expansion in w_0w_aCDM
AU - Tommaso Moretti
AU - Noemi Frusciante
AU - Giovanni Verza
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2607.20257
UR - https://arxiv.org/abs/2607.20257
AB - We investigate the effect of local cosmic voids on low-redshift measurements of the Hubble rate in flat w_0w_aCDM cosmologies. Using a hydrodynamical model for isolated spherical inverse top-hat underdensities, we compute the void-induced Hubble shift as a function of redshift, enclosed density contrast δ_E and cosmological parameters. We find that the effect is mainly controlled by the matter sector, through δ_E and Ω_m,0, while dynamical dark energy gives only subdominant late-time corrections. For a Planck-calibrated ΛCDM background, matching the SH0ES value requires a present-day void with δ_E(z=0)≃ −0.44, substantially deeper than the KBC-like local underdensity. A KBC-like void lowers the SH0ES-Planck discrepancy to about 2σ, but is not deep enough to fully reconcile the two measurements. Allowing for dynamical dark energy, including regions motivated by recent DES and DESI analyses, changes this result only at the percent level. We also show that the reported redshift dependence of locally inferred H_0 values can be represented phenomenologically by an effective enclosed matter profile. This reconstruction should be interpreted as a consistency test of local-structure effects rather than as explanation for an evolving background value of H_0. Overall, local underdensities can affect low-redshift Hubble-rate inferences, but they do not resolve the Hubble tension within the spherical void setup considered here.
ER -