PACT I: Combining ACT and Planck data for optimal detection of tSZ signal

N. Aghanim (1) , M. Douspis (1) , G. Hurier , D. Crichton , J.-M. Diego , M. Hasselfield , J. Macias-Perez (2) , T. A. Marriage , E. Pointecouteau (3) , M. Remazeilles , E. Soubrié (1)

1 IAS - Institut d'astrophysique spatiale
2 LPSC - Laboratoire de Physique Subatomique et de Cosmologie
3 IRAP - Institut de recherche en astrophysique et planétologie

We present the optimal reconstruction of the thermal Sunyaev-Zel'dovich (tSZ) effect signal based on the combination of a heterogeneous dataset consisting of ACT and Planck data, with different numbers of channels, angular resolutions and noise levels. We combine both datasets using two different approaches, a Matched Multi-Filter (MMF) technique and an optimised 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 SZ signal improves by up to a factor of three. In the case of the optimised ILC method, we show that the tSZ map is reconstructed with a resolution of $\sim 1.5$ arcmin. This is more than a factor two improvement compared with the Planck resolution, and with a very good control of noise, i.e. 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.

Mots clés: Astrophysics - Cosmology and Nongalactic Astrophysics

Domaines: Astrophysique [astro-ph]

N. Aghanim, M. Douspis, G. Hurier, D. Crichton, J.-M. Diego, et al.. PACT I: Combining ACT and Planck data for optimal detection of tSZ signal. Astronomy and Astrophysics - A&A, 2019, 632, pp.A47. ⟨10.1051/0004-6361/201935271⟩. ⟨hal-02322557⟩