Astrophysics Colloquium: From Cosmological Tensions to Clarity: Illuminating the Dark Universe with Rubin and the CMB

The coming decade will be pivotal for cosmology, with tremendous opportunities and challenges. Rubin Observatory and Simons Observatory will deliver transformative large-scale structure and cosmic microwave background (CMB) datasets. At the same time, artificial intelligence is poised to transform the way we interact with these datasets and infer physics and astrophysics from them.

However, current cosmological inferences are already systematics-limited and confusing. High and low redshifts, large and small scales, disagree as to the amount of matter and fluctuations in the Universe, resulting in surprisingly low neutrino masses, degenerate with a possibly-evolving dark energy (often with phantom crossing).

How can we infer reliable physics from the increasingly precise, multisurvey and multimodal cosmological data? I will present promising ways to unlock the full statistical power of LSST through CMB cross-correlations, by disentangling baryons from dark matter, neutrinos from dark energy, and by rigorously controlling key systematics including foregrounds, shear calibration, and photometric redshift errors. New machine learning methods will play an important role in this effort.