Pressure distribution of the high-redshift cluster of galaxies CL J1226.9+3332 with NIKA ^⋆

¹ Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Grenoble-Alpes, CNRS/IN2P3, 53 avenue des Martyrs, 38026 Grenoble, France
e-mail: adam@lpsc.in2p3.fr
² Institut de RadioAstronomie Millimétrique (IRAM), 38406 Grenoble, France
³ Astronomy Instrumentation Group, University of Cardiff, UK
⁴ Laboratoire AIM, CEA/IRFU, CNRS/INSU, Université Paris Diderot, CEA-Saclay, 91191 Gif-Sur-Yvette, France
⁵ Institut d’Astrophysique Spatiale (IAS), CNRS and Université Paris Sud, 91405 Orsay, France
⁶ Institut d’Electronique Fondamentale (IEF), Université Paris Sud, 91405 Orsay, France
⁷ Institut Néel, CNRS and Université de Grenoble, 38000 Grenoble, France
⁸ Institut de RadioAstronomie Millimétrique (IRAM), Granada, Spain
⁹ Univ. Grenoble Alpes, IPAG, 38000 Grenoble, France
¹⁰ CNRS, IPAG, 38000 Grenoble, France
¹¹ Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France
¹² CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
¹³ University College London, Department of Physics and Astronomy, Gower Street, London WC1E 6BT, UK
¹⁴ School of Earth and Space Exploration and Department of Physics, Arizona State University, Tempe, AZ 85287, USA
¹⁵ Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy

Received: 10 October 2014
Accepted: 28 November 2014

Abstract

The thermal Sunyaev-Zel’dovich (tSZ) effect is expected to provide a low scatter mass proxy for galaxy clusters since it is directly proportional to the cluster thermal energy. The tSZ observations have proven to be a powerful tool for detecting and studying them, but high angular resolution observations are now needed to push their investigation to a higher redshift. In this paper, we report high angular (<20 arcsec) resolution tSZ observations of the high-redshift cluster CL J1226.9+3332 (z = 0.89). It was imaged at 150 and 260 GHz using the NIKA camera at the IRAM 30-m telescope. The 150 GHz map shows that CL J1226.9+3332 is morphologically relaxed on large scales with evidence of a disturbed core, while the 260 GHz channel is used mostly to identify point source contamination. NIKA data are combined with those of Planck and X-ray from Chandra to infer the cluster’s radial pressure, density, temperature, and entropy distributions. The total mass profile of the cluster is derived, and we find M₅₀₀ = 5.96^+1.02_-0.79 × 10¹⁴M_⊙ within the radius R₅₀₀ = 930⁺⁵⁰_-43 kpc, at a 68% confidence level. (R₅₀₀ is the radius within which the average density is 500 times the critical density at the cluster’s redshift.) NIKA is the prototype camera of NIKA2, a KIDs (kinetic inductance detectors) based instrument to be installed at the end of 2015. This work is, therefore, part of a pilot study aiming at optimizing tSZ NIKA2 large programs.