02 February 2021Séminaire – Nicolas Martinet (LAM)

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Probing dark energy with cosmic shear

Abstract
Understanding the accelerated expansion of the Universe is one of the most important challenges of modern cosmology. Thanks to the development of large dedicated surveys (Euclid, Rubin/LSST, Roman/WFIRST), weak-lensing cosmic shear offers the possibility to answer this question by constraining the dark energy equation of state (w). In this presentation, I will introduce cosmic shear and its application to current state-of-the-art surveys: the Kilo Degree Survey (KiDS) and the Dark Energy Survey (DES). I will discuss differences between these two surveys and how they impact the so-called cosmological tension observed between cosmic shear and cosmic microwave background constraints. I will then review future prospects to measure w with the Euclid satellite, focusing on the accurate modeling of systematic biases. Finally, I will show that these constraints can be significantly improved by resorting to weak-lensing mass map estimators that additionally probe the non-Gaussian part of the matter distribution.