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

Abstract

We show that, in flat $\Lambda$CDM, low-redshift structure probes -- cluster abundances, 3$\times$2-point analyses, and full-shape clustering -- are mutually consistent, jointly delivering precise constraints on ${\sigma }_8$ and ${\Omega }_{\mathrm{m}}$ that agree with geometrical datasets (CMB+BAO+SN). In $w_0{w}_a$CDM, adding clusters to the geometry dataset reduces the evidence for evolving dark energy while relaxing the $H_0$ tension, suggesting a $\Lambda$CDM evolution of the late-time Universe and a sound horizon that differs from its standard value.

6 pages, 1 page of supplemental material, 4 figures, to be submitted to PRL