PACT

I. Combining ACT and Planck data for improved extraction of tSZ signal

¹ Institut d’Astrophysique Spatiale, CNRS (UMR8617) Université Paris Sud, Bâtiment 121, Orsay, France
e-mail: nabila.aghanim@ias.u-psud.fr
² Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Plaza de San Juan, 1, Planta 2, 44001 Teruel, Spain
³ Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Durban 4041, South Africa
⁴ Instituto de Física de Cantabria (CSIC-UC), Avda. Los Castros s/n, 39005 Santander, Spain
⁵ Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA
⁶ Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802, USA
⁷ LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, 53 Av. des Martyrs, 38026 Grenoble, France
⁸ Dept. of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
⁹ IRAP, Université de Toulouse, CNRS, CNES, UPS, Toulouse, France
¹⁰ Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK

Received: 14 February 2019
Accepted: 16 May 2019

Abstract

We present the optimal reconstruction of the thermal Sunyaev–Zel’dovich (tSZ) effect signal based on the combination of a heterogeneous dataset consisting of Atacama Cosmology Telescope (ACT) and Planck data, with different numbers of channels, angular resolutions, and noise levels. We combine both datasets using two different approaches, a matched multifilter (MMF) technique and an optimized internal linear combination (ILC). We show that when applying the MMF to the combination of ACT and Planck data, the size-flux degeneracy is reduced and the signal-to-noise of clusters detected with their Sunyaev–Zel’dovich (SZ) signal improves by up to a factor of three. In the case of the optimized ILC method, we show that the tSZ map is reconstructed with a resolution of ∼1.5 arcmin. This is more than a factor two improvement compared with the Planck resolution, and with a very good control of noise, meaning that it is limited only by the intrinsic noise of the individual experiments. The combination of ACT and Planck data offers a unique opportunity to improve on the study of the pressure profiles and to study substructure in clusters through their tSZ.