Testing ΛCDM with forthcoming SPT-3G measurements of CMB and CMB lensing power spectra*

The South Pole Telescope (SPT) is a 10m telescope specifically engineered for low-noise and high-angular-resolution measurements of the millimeter-wave sky. In this talk, we describe the surveys currently being conducted with the SPT and its third-generation camera (SPT-3G) and how they can be used to test the ΛCDM model in several ways. Based on achieved performance, we forecast expected uncertainties on temperature and E-mode polarization power spectra, their cross power spectrum, and the gravitational lensing power spectrum. We also propagate the power spectrum uncertainties forward to constraints on cosmological parameters. We find that, assuming ΛCDM, data from SPT-3G alone enable about two orders of magnitude of reduction in the allowed six-dimensional parameter volume relative to the volume allowed by Planck data. Given that these constraints come from signals largely different from those measured by Planck (more weight on smaller scales, polarization, and gravitational lensing), a consistency test with Planck parameter estimates will be a significant test of the ΛCDM model. We will also discuss some proposed alternatives to the ΛCDM model that reduce the S8 or H0 tensions and discuss the potential of the SPT-3G surveys to test these models.