Institute for Advanced Study Informal Astrophysics Seminar

The Atacama Cosmology Telescope (ACT) has mapped the microwave sky to arcminute scales. Efficient map-making and spectrum-estimation techniques allow us to probe the acoustic peaks deep into the damping tail, and allow for confirmation of the concordance model, and tests for deviations from the standard cosmological picture. We present constraints on a variety of cosmological parameters using the 3-year ACT dataset. We re-analyze the Planck data and find that the 217GHz x 217GHz detector set spectrum used in the Planck analysis is responsible for some of the tension between the Planck parameters and other astronomical measurements. We will describe our map-based foreground cleaning procedure, which relies on a combination of 353 GHz and 545 GHz maps to reduce residual foregrounds in the intermediate frequency maps used for cosmological inference. We compare our cleaning procedure with the foreground modeling used by the Planck team and find good agreement. The difference in parameters between our analysis and that of the Planck team is mostly due to our use of cross-spectra from the publicly available survey maps instead of their use of the detector set cross-spectra which include pixels only observed in one of the surveys. We show evidence suggesting residual systematics in the detector set spectra used in the Planck likelihood code, which are substantially reduced for our spectra.