NIKA2 Performance and Cosmology Program with Galaxy Clusters

TL;DR

NIKA2 is a high-resolution millimetric camera that maps the thermal Sunyaev-Zel'dovich effect in galaxy clusters, enabling precise cosmological measurements through its large program and initial successful observations.

Contribution

This paper presents the commissioning, capabilities, and initial results of NIKA2, a new instrument for detailed SZ effect mapping in galaxy clusters, advancing cosmological studies.

Findings

First SZ map of a galaxy cluster with NIKA2

Detected significant impact of intracluster medium dynamics on SZ observables

Demonstrated NIKA2's potential for precise mass-observable relation characterization

Abstract

NIKA2 is a dual-band millimetric camera of thousands of Kinetic Inductance Detectors (KID) installed at the IRAM 30-meter telescope in the Spanish Sierra Nevada. The instrument commissioning was completed in September 2017, and NIKA2 is now open to the scientific community and will operate for the next decade. NIKA2 has well-adapted instrumental design and performance to produce high-resolution maps of the thermal Sunyaev-Zel'dovich (SZ) effect toward intermediate and high redshift galaxy clusters. Moreover, it benefits from a guaranteed time large program dedicated to mapping a representative sample of galaxy clusters via SZ and that includes X-ray follow-ups. The main expected outputs of the SZ large program are the constraints on the redshift evolution of the pressure profile and the mass-observable relation. The first SZ mapping of a galaxy cluster with NIKA2 was produced, as part of the SZ large program. We found a sizable impact of the intracluster medium dynamics on the integrated SZ observables. This shows NIKA2 capabilities for the precise characterisation of the mass-observable relation that is required for accurate cosmology with galaxy clusters.