An Assessment of Contamination in the Thermal-SZ Map Using Cross-correlations

We search for potential galactic and extragalactic dust contamination in thermal Sunyaev-Zeldovich maps derived from the Planck data. To test for contamination, we apply a variety of galactic dust and cosmic infrared background (CIB) models to the data as part of the y map reconstruction process. We evaluate the level of contamination by cross-correlating these y maps with mass tracers based on weak lensing data. The lensing data we use are the convergence map, kappa, from the Red Sequence Cluster Lensing survey, and the cosmic microwave background (CMB) lensing potential map, phi, from the Planck Collaboration. We make a CIB-subtracted y map and measure the cross-correlation between it and the lensing data. By comparing it with CIB-contaminated cross-correlation, we find that the cross-correlation between kappa and y is only slightly contaminated by CIB signal, at the level of 6.8 +/- 3.5%, which implies that previous detections of kappa x y are robust to CIB contamination. However, we find that phi x y is more significantly contaminated, by 16.7 +/- 3.5%, because the CMB lensing potential probes higher redshift sources that overlap more with the CIB sources. We find that Galactic dust does not significantly contaminate either cross-correlation signal.