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 redshift 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-fit model of CIB by the Planck satellite, we estimate that the residual correlation of CIB with large-scale structures will be of an order of $2\%$ 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 a $\sim10-30\%$ level. This is originated from positive cross correlation with radio sources and lensing at $\sim100\, {\rm GHz}$ 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 flat-spectral index are assumed to populate massive cluster-sized dark matte halos. Our results indicate that minor source population in radio bands can play an important role in determining observed tSZ-lensing correlation at $<10$ arcmin.