Galaxy cluster SZ detection with unbiased noise estimation: an iterative approach

• DOI: 10.48550/arxiv.2204.13780
• Publication Date: 2022-01-01
• Authors: Íñigo Zubeldía; Aditya Rotti; Jens Chluba; Richard A. Battye
• Keywords: Noise power

Multi-frequency matched filters (MMFs) are routinely used to detect galaxy clusters from CMB data through the thermal Sunyaev-Zeldovich (tSZ) effect, leading cluster catalogues that can be for cosmological inference. In order applied, MMFs require knowledge of cross-frequency power spectra noise in maps. This is typically estimated and taken equal data, assuming contribution tSZ signal detections negligible. Using both analytical arguments \textit{Planck}-like mock observations, we show doing so causes MMF overestimated, inducing a loss signal-to-noise. Furthermore, observable (the amplitude $\hat{y}_0$ or signal-to-noise $q$) does not behave as expected, which potentially bias particular, becomes biased with respect its theoretical prediction displays variance also differs predicted value. We propose an iterative (iMMF) approach designed mitigate these effects. this approach, after first standard step, reestimated by masking delivering updated catalogue. Applying our iMMF find aforementioned effects completely suppressed. leads gain relative MMF, more significant higher number them, expected properties, thus eliminating any potential biases constraints.