Extracting the thermal SZ signal from heterogeneous millimeter data sets

Abstract

Complementarily to X-ray observations, the thermal SZ effect is a powerful tool to probe the baryonic content of galaxy clusters from their core to their peripheries. While contaminations by astrophysical and instrumental backgrounds require us to scan the thermal SZ signal across various frequencies, the multi-scale nature of cluster morphologies require us to observe such objects at various angular resolutions. We developed component separation algorithms that take advantage of sparse representations to combine these heterogeneous pieces of information, separate the thermal SZ signal from its contaminants, detect and map the thermal SZ signal of galaxy clusters from nearby to more distant clusters of the Planck catalogue. Spatially weighted likelihoods allow us in particular to connect parametric fittings of the component Spectral Energy Distribution with wavelet and curvelet imaging, but also to combine signals registered with beams of various width. Such techniques already allow us to detect sub-structures in the peripheries of nearby clusters with Planck, and could be extended to observations performed at higher angular resolutions.

The NuSTAR, XMM-Newton, and Suzaku View of A3395 at the Intercluster Filament Interface

“…The intercluster filament has also recently been confirmed and studied in detail with eROSITA (Reiprich et al 2021). Furthermore, this network has been mapped by Chandra and through the thermal Sunyaev-Zel'dovich (SZ) effect using the Planck High Frequency Instrument by Bourdin et al (2020), which clearly shows the intercluster filament connected to the ICM of both clusters. These clusters are thought to have already begun interacting via this filament and might be at a pre-merger stage (Sugawara et al 2017).…”

“…Guided by the literature (Tittley & Henriksen 2001;Lakhchaura et al 2011;Planck Collaboration et al 2013;Bourdin et al 2020;Reiprich et al 2021), we studied Regions A, B, and C in detail with the assumption that these regions may represent an interface of the A3395 ICM and the intercluster filament. 4 cm −3 for the intercluster filament.…”

Constraining cosmology with a new all-sky Compton parameter map from the Planck PR4 data

“…The tSZ signal is subdominant relative to the CMB and other foreground emissions in the Planck frequency bands. Thus tailored component separation algorithms are required to reconstruct the tSZ map (i.e., Remazeilles et al 2011;Hurier et al 2013;Bourdin et al 2020;Bonjean 2020). We adopted the MILCA (Modified Internal Linear Combination Algorithm) (Hurier et al 2013) used for one of the Planck 𝑦-map reconstructions in Planck Collaboration (2016a) and mostly followed their reconstruction procedure (the difference in the procedure is summarized at the end of Sect.…”

“…The thermal Sunyaev-Zel'dovich (tSZ) effect (Sunyaev & Zeldovich 1972) is due to the inverse Compton scattering of cosmic microwave background (CMB) photons by hot electrons along the line of sight and in particular in clusters of galaxies. The tSZ effect has been measured by the Planck satellite, the Atacama Cosmology Telescope (ACT), and the South Pole Telescope (SPT) in a large field, and Compton parameter maps (i.e., Planck Collaboration 2014b, 2016aAghanim et al 2019;Madhavacheril et al 2020;Bleem et al 2021), referred to as 𝑦-map, have been constructed thanks to optimized component separation methods (i.e., Remazeilles et al 2011;Hurier et al 2013;Bourdin et al 2020;Bonjean 2020).…”