Extremes of the Cosmic Web: Novel Cosmology with Clusters and Voids
Astronomy and astrophysics
Friday 18 December 2015
to 11:30 at
Martin Sahlén (Oxford University)
Combining galaxy cluster and void abundances breaks the degeneracy between mean matter density Ωm and power spectrum normalization σ8. Consistent with Planck, we constrain Ωm = 0.21 ± 0.10 and σ8 = 0.95 ± 0.21 in a flat ΛCDM universe, using extreme-value statistics on the claimed largest cluster and void. The two-object detection of dark energy is the first cosmological constraint based on void abundances, and is independent 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, but also generic dark energy, neutrino masses, and inflation. Future surveys with eRosita, Athena, Euclid, the Square Kilometer Array, the Large Synoptic Survey Telescope, and WFIRST, will yield catalogues of hundreds of thousands clusters and voids. This will enable novel precision tests of astrophysics and cosmology.