Cross-correlation of radio galaxies with the lensing of the Cosmic Microwave Background (CMB) offers an exciting approach to determining the properties of radio sources. CMB lensing is an unbiased tracer of the integrated matter fluctuations along the line of sight. The lensing-radio cross-correlation can be hence be used to calibrate clustering studies, offering an insight into the history and evolution of the observed radio sources. Cross-correlations are robust to systematics particular to each experiment and are thus a valuable tool for validating auto-correlation measurements derived from each dataset individually.

I will present the results of a recent study which correlates the positions of radio galaxies in the FIRST survey with CMB lensing convergence estimated from the Atacama Cosmology Telescope (arXiv:1502.06456). I will outline what this means for the high-redshift bias of Active Galactic Nuclei and highlight the future science prospects of this measurement for upcoming CMB and radio surveys.