Impact of radio sources and cosmic infrared background on thermal Sunyaev-Zel'dovich - gravitational lensing cross-correlation

Abstract

Cross-correlation with thermal Sunyaev-Zel'dovich (tSZ) effect in cosmic microwave background observation and weak gravitational lensing effect in galaxy imaging survey opens a new window on constraining matter contents in the Universe at redshifts less than 1. In this paper, we study the impact of radio sources and cosmic infrared background (CIB) on observed tSZ-lensing correlation. Assuming the best-fitting model of CIB by the Planck satellite, we estimate that the residual correlation of CIB with large-scale structures will be of the order of 2 per cent of expected tSZ-lensing correlation from intracluster medium in current lensing surveys. On the other hand, despite large model uncertainties, we find that correlation of lensing and radio sources can induce a negative correction for the observed tSZ-lensing correlation with an ∼10-30 per cent level. This is originated from positive cross-correlation with radio sources and lensing at ∼100 GHz frequency, whereas tSZ-lensing correlation should show a negative value in temperature fluctuations at that frequency. We also show that the negative correction by radio-lensing correlation can solve the tension between recent measurements of tSZ-lensing correlation and an expected signal from 'universal' gas pressure profile of nearby galaxy clusters, when the radio sources with a flat-spectral index are assumed to populate massive cluster-sized dark matter haloes. Our results indicate that minor source population in radio bands can play an important role in determining observed tSZ-lensing correlation at ≾ 10 arcmin.