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.
Highlights
With X-ray emission, the thermal Sunyaev-Zel’dovich signal is a powerful tracer of the hot gas content of galaxy clusters, of the deep gravitational potential well that these hot atmospheres fill in
We developed component separation algorithms that take advantage of wavelet and curvelet analyses to denoise and map astrophysical contaminants of the thermal Sunyaev-Zel’dovich (tSZ) signal as detected by Planck High Frequency Instrument (HFI)
Residuals of these contaminants around individual clusters or stacked cluster images show us that thermal dust contamination around high SNR clusters in the Planck catalogue can be modelled by using a three component grey-body, including two components for the Galactic emission and a third component for the cluster emission
Summary
With X-ray emission, the thermal Sunyaev-Zel’dovich (tSZ) signal is a powerful tracer of the hot gas content of galaxy clusters, of the deep gravitational potential well that these hot atmospheres fill in. Due to the quadratic and linear dependences of X-ray surface brightness and millimetre (mm) optical depth of clusters with their hot gas density, X-ray observations mostly enlighten the innermost cluster regions while mm observations reveal us more peripheral regions where the cosmic matter continuously accretes and virialises. Combining these signals allows us to probe the helium abundance in the Intra-Cluster Medium (ICM) or to measure the intrinsic sizes of clusters, to infer the cosmological parameters that underpin their angular diameter distance.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
