# Colloque national Action Dark Energy 2020 - 4ème édition

Oct 13 – 15, 2020
Europe/Paris timezone

## High-resolution SZ observations for cluster cosmology with NIKA2

Oct 15, 2020, 12:25 PM
20m
en visio

### en visio

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### Speaker

Florian Kéruzoré (LPSC)

### Description

As the largest and most massive gravitationally bound objects in the universe, galaxy clusters are excellent tracers of cosmic structures evolution, and can therefore be used to probe the underlying cosmological parameters. In order to do so, a careful understanding of the systematic effects involved in the cosmological exploitation of cluster surveys is crucial. One source of such systematic uncertainty comes from the lack of knowledge of galaxy clusters at high redshift. Indeed, few high-$z$ clusters have been imaged with a high angular resolution, preventing us from extracting precise information on their thermodynamic properties, e.g. their mass, pressure and entropy.

NIKA2 is a dual-band camera, containing $\sim\hspace{-2pt}3000$ KIDs (Kinetic Inductance Detectors) operated at $\sim\hspace{-2pt}100\;\mathrm{mK}$ at the IRAM 30m telescope. With its high angular resolution (17.7 and 11.2 arcsec at 150 and 260 GHz respectively) and large field of view (6.5 arcmin), it allows us to map the Sunyaev-Zeldovich (SZ) effect in galaxy clusters with great sensitivity at both small and large angular scales. The NIKA2 SZ Large Program (LPSZ) is currently using the NIKA2 camera to get high-resolution SZ maps of 50 high-redshift clusters, and to infer precise measurements of the thermodynamic properties of their intra-cluster medium. These results will allow us to improve our knowledge of the pressure profile of galaxy clusters and of the scaling relation between cluster mass and SZ signal, which are both essential to cluster-based cosmological analysis. In this talk, I will present the NIKA2 SZ Large Program, along with its first cluster observations.