Evidence of Lensing of the Cosmic Microwave Background by Dark Matter Halos

solar mass dark matter halos. Lensing convergence maps from the Atacama Cosmology TelescopePolarimeter (ACTPol) are stacked at the positions of around 12,000 optically-selected CMASSgalaxies from the SDSS-III/BOSS survey. The mean lensing signal is consistent with simulated darkmatter halo pro les, and is favored over a null signal at 3:2˙signi cance. This result demonstratesthe potential of microwave background lensing to probe the dark matter distribution in galaxy groupand galaxy cluster halos.INTRODUCTION