Speaker
Description
The Atacama Cosmology Telescope (ACT) collaboration presents cosmological constraints and data products from its sixth data release, DR6. Including data from 2017 - 2022 (the telescope decommissioning), DR6 observed 40% of the microwave sky to five times the angular resolution and three times the depth in polarization as the Planck satellite. The improved cosmic microwave background (CMB) measurements at small scales complement the larger-scale information from Planck. We use these datasets, along with tracers of large-scale-structure (CMB lensing) and cosmic expansion (baryon acoustic oscillations, or BAO), to probe the fundamental physics of the Universe across epochs and scales. A joint analysis of these data reveals $H_0 = 68.22 \pm 0.36~\rm km/s/Mpc$ and $\sigma_8 = 0.813 \pm 0.005$, consistent with prior analyses of the CMB, CMB lensing, and BAO. We find no deviation from a flat Universe. More generally, in tests of over 30 extensions to the Lambda Cold Dark Matter (LCDM) model, we find the CMB does not significantly prefer any departures from LCDM. Finally, this talk discusses the ACT results in the context of updated BAO measurements from the Dark Energy Spectroscopic Instrument (DESI), made public following DR6. We release DR6 maps in three frequency bands (located around 90, 150, and 220 GHz) as well as CMB power spectrum likelihoods.
