Stress-testing LCDM and Searching for New Physics using CMB observations
Kimmy Wu
University of Chicago

The Lambda cold dark matter (LCDM) paradigm has been successful in sufficiently describing all cosmological observations. However, new data are beginning to challenge the validity of the model. For example, the value of the Hubble constant (H0) inferred from the Planck satellite and that measured using the classical distance ladder are now discrepant at the > 3 sigma level, suggesting a breakdown of LCDM if systematics are ruled out as viable explanations. One way to shed light on this tension is to get independent LCDM/H0 measurements from different experiments. In this talk, I will show results from CMB measurements of the South Pole Telescope's (SPT) two generations of receiver: SPT-SZ and SPTpol. From SPT-SZ, I will argue that parameter differences from modes common between Planck and SPT-SZ are consistent with noise fluctuations. With SPTpol, I will highlight a couple of parameter trends our data prefer, for example, a high-H0 preference when including small angular scale data. I will then discuss what kind of modification of LCDM could reconcile the Hubble discrepancy. Finally, I will conclude with possibilities that lie ahead with new data coming in from SPT-3G.