CLUSTER–VOID DEGENERACY BREAKING: DARK ENERGY, PLANCK, AND THE LARGEST CLUSTER AND VOID

Abstract

Combining galaxy cluster and void abundances breaks the degeneracy between mean matter density and power-spectrum normalization . For the first time for voids, we constrain and for a flat Λ CDM universe, using extreme-value statistics on the claimed largest cluster and void. The Planck -consistent results detect dark energy with two objects, independently of other dark energy probes. Cluster–void studies are also complementary in scale, density, and nonlinearity, and are of particular interest for testing modified-gravity models.