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arXiv · 1511.04075

Cluster-Void Degeneracy Breaking: Dark Energy, Planck and the Largest Cluster & Void

Martin Sahlén·Íñigo Zubeldía·Joseph Silk
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Abstract

Combining galaxy cluster and void abundances breaks the degeneracy between mean matter density $\Omega_{\rm m}$ and power spectrum normalization $\sigma_8$. In a first for voids, we constrain $\Omega_{\rm m} = 0.21 \pm 0.10$ and $\sigma_8 = 0.95 \pm 0.21$ for a flat $\Lambda$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 also offer complementarity in scale, density, and non-linearity - of particular interest for testing modified-gravity models.

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Martin Sahlén, Íñigo Zubeldía, Joseph Silk. 2015-11-12. Cluster-Void Degeneracy Breaking: Dark Energy, Planck and the Largest Cluster & Void. https://doi.org/10.3847/2041-8205%2F820%2F1%2Fl7

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