[séminaire] Using galaxy clusters as cosmological probes

by Marina Ricci

Tuesday 14 May 2019, 11:00 → 12:00 Europe/Paris

Grand Amphi (LPSC)

Addressing fundamental questions regarding our understanding of the Universe, such as the cause of its accelerated expansion or the nature of dark matter, requires to confront theories and observations. In this context, galaxy clusters can be used as powerful cosmological probes and unique fundamental physics laboratories. However, their current utilization is limited by uncertainties and systematics, notably affecting the measurement of their masses. The challenge to fully exploit upcoming surveys undertaken in the optical/NIR (e.g. LSST, Euclid), X-ray (e.g. eROSITA) and millimeter regime (e.g. CMB-S4) is thus to control and lower down any bias related to their formation and evolution. After giving a brief overview of the status of cluster cosmology, I will present the optical characterization of a statistical sample of X-ray detected clusters, covering a wide range of masses and redshifts, and what can be learned in terms of cluster modeling and detection. I will then focus on an observational project I am co-leading, aiming at mapping three distants X-ray clusters in the millimetre regime, with the NIKA2 camera. The goal is to achieve a multi-wavelength characterization of those systems and to test if they deviate from the expectations of standard evolution of clusters. Finally, I will introduce prospective analyses for LSST, before concluding on the opportunities and challenges for cluster cosmology in the coming years.