Cosmology with the Euclid galaxy bispectrum
The last decades witnessed huge progress in understanding the large-scale structure of the Universe. While homogeneous and isotropic on the largest scales, the matter and galaxy distributions display complex patterns on smaller scales where we observe elongated filaments, compact clusters and volume-filling underdense regions. These features are not captured by studies of two-point statistics like the power spectrum that does not retain information on the phases of the Fourier modes of the density field. Therefore, higher-order statistics like the bispectrum should provide additional information. The Euclid galaxy redshift survey will cover a large enough volume to provide robust measurements of the galaxy bispectrum as a function of redshift. The potential of these measurements as a mean to extract additional cosmological information has never been investigated properly. In this talk we present detailed forecasts for the Euclid mission. Our study shows that there is a clear advantage in combining the power spectrum and the bispectrum to infer the galaxy bias parameters and constrain the dark-energy equation of state.
Victoria Yankelevich & Vivien Thiel