2015 Planck 2015 results XXIV 2016 Bocquet et al. 2013 Planck 2013 results XX 2014 Bleem et al. 2021), and as a result they have also played an important role in the cosmological analyses based on these cluster samples (e.g. 2015 Planck 2015 results XXVII 2016 Hilton et al. 2013 Planck 2013 results XXIX 2014 Bleem et al. Indeed, matched filters have been used in the construction of the cluster catalogues derived from SPT, ACT, and Planck data (e.g. 2002 Melin, Bartlett & Delabrouille 2006), matched filters have become a standard tool with which to detect and characterize galaxy clusters from CMB observations via their thermal Sunyaev–Zeldovich (tSZ) signature. Galaxies: clusters: general, cosmology: observations, diffuse radiation 1 INTRODUCTIONįirst proposed in the galaxy cluster context more than two decades ago (Haehnelt & Tegmark 1996 Herranz et al. We also consider the impact of the bias on the cluster number counts of Planck and the Simons Observatory (SO), finding it to be negligible for the former and potentially significant for the latter. After reviewing the general mathematical formalism underlying matched filters, we study the statistics of the signal-to-noise with a set Monte Carlo mock observations, finding it to be well-described by a unit-variance Gaussian for signal-to-noise values of 6 and above, and quantify the magnitude of the optimization bias, for which we give an approximate expression that may be used in practice. Both aspects arise from the fact that the signal-to-noise is constructed through an optimization operation on noisy data, and hold even if the cluster signal is modelled perfectly well, no foregrounds are present, and the noise is Gaussian.

In this work, we show that this observable is, in general, non-Gaussian, and that it suffers from a positive bias, which we refer to as optimization bias.

In addition, they naturally provide an observable, the detection signal-to-noise or significance, which can be used as a mass proxy in number counts analyses of tSZ-selected cluster samples.

Matched filters are routinely used in cosmology in order to detect galaxy clusters from mm observations through their thermal Sunyaev–Zeldovich (tSZ) signature.

What does opt in mean on astro