Abstract

We present new arcminute-resolution maps of the Cosmic Microwave Background temperature and polarization anisotropy from the Atacama Cosmology Telescope, using data taken from 2013-2016 at 98 and 150 GHz. The maps cover more than 17,000 deg(2), the deepest 600 deg(2) with noise levels below 10 mu K-arcmin. We use the power spectrum derived from almost 6,000 deg(2) of these maps to constrain cosmology. The ACT data enable a measurement of the angular scale of features in both the divergence-like polarization and the temperature anisotropy, tracing both the velocity and density at last-scattering. From these one can derive the distance to the last-scattering surface and thus infer the local expansion rate, H-0. By combining ACT data with large-scale information from WMAP we measure H-0 = 67.6 +/- 1.1 km/s/Mpc, at 68% confidence, in excellent agreement with the independently-measured Planck satellite estimate (from ACT alone we find H-0 = 67.9 +/- 1.5 km/s/Mpc). The Lambda CDM model provides a good fit to the ACT data, and we find no evidence for deviations: both the spatial curvature, and the departure from the standard lensing signal in the spectrum, are zero to within 1 sigma; the number of relativistic species, the primordial Helium fraction, and the running of the spectral index are consistent with Lambda CDM predictions to within 1.5-2.2 sigma. We compare ACT, WMAP, and Planck at the parameter level and find good consistency; we investigate how the constraints on the correlated spectral index and baryon density parameters readjust when adding CMB large-scale information that ACT does not measure. The DR4 products presented here will be publicly released on the NASA Legacy Archive for Microwave Background Data Analysis.