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What Galaxy Clusters Have to Say About Dynamical Dark Energy and $H_0$

Andrés N. Salcedo, Eduardo Rozo, Hao-Yi Wu, Shulei Cao, Enrique Paillas, Hanyu Zhang, Eli S. Rykoff

Abstract

We show that, in flat $Λ$CDM, low-redshift structure probes -- cluster abundances, 3$\times$2-point analyses, and full-shape clustering -- are mutually consistent, jointly delivering precise constraints on $σ_8$ and $Ω_{\rm m}$ that agree with geometrical datasets (CMB+BAO+SN). In $w_0w_a$CDM, adding clusters to the geometry dataset reduces the evidence for evolving dark energy while relaxing the $H_0$ tension, suggesting a $Λ$CDM evolution of the late-time Universe and a sound horizon that differs from its standard value.

What Galaxy Clusters Have to Say About Dynamical Dark Energy and $H_0$

Abstract

We show that, in flat CDM, low-redshift structure probes -- cluster abundances, 32-point analyses, and full-shape clustering -- are mutually consistent, jointly delivering precise constraints on and that agree with geometrical datasets (CMB+BAO+SN). In CDM, adding clusters to the geometry dataset reduces the evidence for evolving dark energy while relaxing the tension, suggesting a CDM evolution of the late-time Universe and a sound horizon that differs from its standard value.

Paper Structure

This paper contains 3 sections, 2 equations, 4 figures, 1 table.

Table of Contents

  1. Supplemental Material
  2. Choice of Experiments
  3. Combining Experiments

Figures (4)

  • Figure 1: Left and center: Constraints from low-redshift experiments, as labeled in the legend. Right: Combined constraints from Combo-1 and Combo-2. The gray ellipse shows Planck CMB constraints for flat $\Lambda$CDM, while the black contours add DESI BAO and DES Y5 SN to define the geometry-only data set.
  • Figure 2: Left: Constraints from DES Y1 clusters and geometry in the $\sigma_8$–$\Omega_{\rm m}$ plane for $\Lambda$CDM and $w_0$–$w_a$ models. Right: 68% and 95% contours of the geometry-only posterior in $w_0$–$w_a$, with random samples color coded by $\Omega_{\rm m}$. See text for discussion.
  • Figure 3: Posteriors for geometry-only and geometry+clusters in $w_0$–$w_a$ (left) and $\Omega_{\rm m}$–$h$ (right). Also shown are the $H_0$ constraints from SH0ES shoes25 and CCHP cchp25. The left panel also shows the definition of $D_w$, the distance from $\Lambda$CDM along the line $3(1+w_0)+w_a=0$ (dashed black). The light gray ellipse shows the region where the clusters emulator is valid.
  • Figure 4: Left: Posterior distributions of $D_w$ for the DES clusters, geometry, and geometry+clusters data sets. Also shown is the prior in $D_w$ used to avoid emulator extrapolation in the clusters-only run (see text). The combined geometry+clusters chain uses a flat prior in all cosmological parameters. Right: The corresponding posterior distributions in the $D_w$-$\Omega_{\rm m}$ plane. The gray ellipse shows the parameter space over which the clusters emulator interpolates rather than extrapolates.