CMB Lensing at Sub-Percent Precision: A New Probe of Cosmology and Fundamental Physics

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Maps of the gravitational lensing of the cosmic microwave background (CMB) directly trace the mass distribution across our universe. Though recent measurements have established the CMB lensing signal as a powerful probe of cosmology and fundamental physics, we are only beginning to exploit its scientific potential. My ERC-funded team will analyse lensing in CMB data from Advanced ACTPol and Simons Observatory, powerful ground-based experiments for which I am co-leading the lensing working groups. By developing and applying new analysis methods, my team will reconstruct large-sky CMB lensing maps that are an order of magnitude more precise than current state-of-the-art measurements. With our high-fidelity lensing maps, we will address key questions about the origin of the universe, the properties of neutrinos, the nature of dark energy, and the formation of cosmic structure. We will determine or tightly bound the unknown neutrino mass by measuring the CMB lensing power spectrum to 0.6% precision, place stringent constraints on the time evolution of dark energy by combining CMB lensing maps with large-scale structure datasets, and enable powerful searches for primordial gravitational waves by removing the limiting lensing signal from the CMB polarization. To achieve these goals, my group will address the central challenges posed by the advance of lensing science to ultra-high precision, pioneering new approaches to lensing estimation, foreground mitigation, and CMB B-mode delensing.