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Séminaires, soutenances

Precision Cosmology with Cosmic Voids

by Dr. Alice Pisani (CPPM (Marseille) and IAP (Paris))

jeudi 2 mars 2017 de à (Europe/Paris)
at Salle du 1er étage
Modern surveys allow us to access to high quality measurements, by sampling the galaxy distribution in detail also in the emptier regions, voids. 

Cosmic voids present themselves as a new tool to constrain cosmology. While the treatment of systematics might be simpler in these empty regions, with the aim of achieving the level of precision cosmology a careful modeling of such effects is necessary. In particular, peculiar velocities affect the way we observe cosmic voids, and thus their effect needs to be understood. Using mock catalogues, I analyze the effect of peculiar velocities on void properties.

In this talk, I first briefly describe the algorithm to find voids in galaxy surveys. I then present the results of the analysis of the systematic effects affecting voids and discuss it in the framework of current and future surveys. Additionally, I present a forecast for void abundances with the future Euclid and WFIRST missions and obtain, using the Fisher matrix formalism, a prediction for the constraints that voids will set on cosmological parameters. Finally I show that combining voids with constraints obtained from supernovae measured by LSST is a powerful degeneracy-breaking tool to constrain the dark energy equation of state.