A comparison of algorithms for the construction of SZ cluster catalogues

Abstract

We evaluate the construction methodology of an all-sky catalogue of galaxy clusters detected through the Sunyaev-Zel'dovich (SZ) effect. We perform an extensive comparison of twelve algorithms applied to the same detailed simulations of the millimeter and submillimeter sky based on a Planck-like case. We present the results of this "SZ Challenge" in terms of catalogue completeness, purity, astrometric and photometric reconstruction. Our results provide a comparison of a representative sample of SZ detection algorithms and highlight important issues in their application. In our study case, we show that the exact expected number of clusters remains uncertain (about a thousand cluster candidates at |b| > 20 deg with 90% purity) and that it depends on the SZ model and on the detailed sky simulations, and on algorithmic implementation of the detection methods. We also estimate the astrometric precision of the cluster candidates which is found of the order of ∼2 arcmin on average, and the photometric uncertainty of about 30%, depending on flux.

Planck2013 results. XXI. Power spectrum and high-order statistics of thePlanckall-sky Compton parameter map

“…This match of 52 to 77% per cent, respectively. This is consistent with the results in Melin et al (2012), which show that indirect detection methods based on reconstructed y-maps are less efficient at extracting clusters of galaxies than dedicated direct methods such as those used to build the Planck catalogue of SZ sources (i.e., MMF1, MMF3 and PwS, Herranz et al 2002;Melin et al 2006b;Carvalho et al 2012; Planck Collaboration XXIX 2014).…”

Planck2013 results. XXIX. ThePlanckcatalogue of Sunyaev-Zeldovich sources

“…These algorithms were described and tested using simulations (Melin et al 2012). They were used to construct the Early SZ (ESZ) Planck sample by Planck Collaboration VIII (2011).…”

“…All three assume priors on the cluster spectral and spatial characteristics, which optimize the SZ detection by enhancing the SZ contrast over a set of observations containing contaminating signals. In the following we present the cluster model used as a template by the SZ-finder algorithms and we briefly describe the three detection methods (for details we refer the reader to Herranz et al 2002;Melin et al 2006Melin et al , 2012Carvalho et al 2009Carvalho et al , 2012.…”

CARMA observations of massivePlanck-discovered cluster candidates atz≳ 0.5 associated withWISEoverdensities: breaking the size–flux degeneracy

“…The values were derived using a multifrequency matched filter (Melin et al 2006(Melin et al , 2012. The y profile from Equation 4 is integrated over the cluster profile and then convolved with the Planck beam at the corresponding frequency; the matched filter leverages only the Planck high frequency instrument (HFI) data between 100-857 GHz because it has been seen that the large beams at lower frequencies result in dilution of the temperature decrement due to the cluster.…”