Simulations of cm-wavelength Sunyaev-Zel'dovich galaxy cluster and point source blind sky surveys and predictions for the RT32/OCRA-f and the Hevelius 100-m radio telescope

Abstract

We investigate the effectiveness of blind surveys for radio sources and galaxy cluster thermal Sunyaev-Zel'dovich effects (TSZEs) using the four-pair, beam-switched OCRA-f radiometer on the 32-m radio telescope in Poland. The predictions are based on mock maps that include the cosmic microwave background, TSZEs from hydrodynamical simulations, and unresolved radio sources. We estimate the effects of source clustering towards galaxy clusters from NVSS source counts around Planck-selected cluster candidates, and include appropriate correlations in our mock maps. The study allows us to quantify the effects of halo line-of-sight alignments, source confusion, and telescope angular resolution on the detections of TSZEs. We perform a similar analysis for the planned 100-m Hevelius radio telescope (RTH) equipped with a 49-beam radio camera. We find that RT32/OCRA-f will be suitable for small-field blind radio source surveys, and will detect $33^{+17}_{-11}$ new radio sources brighter than 0.87 mJy at 30~GHz in a 1 deg$^2$ field at $>5\sigma$ CL during a one-year, non-continuous, observing campaign, taking account of Polish weather conditions. It is unlikely that any galaxy cluster will be detected at $3\sigma$ CL in such a survey. A $60$-deg$^2$ survey, with field coverage of $2^2$ beams per pixel, at 15 GHz with the RTH, would find <1.5 galaxy clusters per year brighter than 60 $\mu$Jy (at $3\sigma$ CL), and would detect about $3.4 \times 10^4$ point sources brighter than 1 mJy at $5\sigma$ CL, with confusion causing flux density errors $\lesssim 2\%$ (20%) in 68% (95%) of the detected sources. A primary goal of the planned RTH will be a wide-area ($\pi$~sr) radio source survey at 15 GHz. This survey will detect nearly $3 \times 10^5$ radio sources at $5\sigma$ CL down to 1.3 mJy, and tens of galaxy clusters, in one year of operation with typical weather conditions. ABRIDGED