HET Seminar Oct 20th: Nils Schonenberg
Nils Schoneberg: A Hubble tension status update
The standard model of cosmology (LCDM) involving cold dark matter and dark energy has been wildly successful in predicting astrophysical observations across a wide range of scales. Despite this success, the precise nature of its ingredients has so far remained elusive. To this end, a vast experimental effort has been undertaken to measure observables in the local and distant universe to unprecedented precision. These promising measurements have only deepened the mysteries of cosmology, however, as they revealed a growing tension between the current expansion rate of the Universe (the Hubble constant) measured through the local distance ladder and that inferred from the cosmic microwave background. Now that the formal significance of this discrepancy has reached a level of five sigma significance, it is crucial to thoroughly re-examine both the astrophysical observations as well as the theoretical models used to analyze the data. In this talk, I introduce the experimental pillars of this Hubble tension and highlight the crucial role that current and future large-scale structure surveys play in this quest. I further discuss the status of the theoretical proposals for easing the Hubble tension, with a focus on a critical examination of the different mechanisms at play in these models.