New Opportunities with Weak Gravitational Lensing

Cosmological surveys will map the sky with unprecedented precision, creating new opportunities to understand the contents and evolution of the Universe. Gravitational lensing, the bending of light by cosmic structure, leaves characteristic imprints in our cosmic maps. Techniques to measure and utilize the effects of gravitational lensing have become increasingly important to maximize the scientific return of modern cosmological surveys. A team of scientists at Southern Methodist University (SMU) and Arizona State University (ASU) will build on these techniques in two distinct ways. First, methods used to search for gravitational lensing will be extended to search for gravitational waves, the ripples in spacetime produced by violent cosmic events like collisions of black holes. Additionally, a new technique for measuring the effects of gravitational lensing of the cosmic microwave background (CMB) will yield new insights to the distribution, and potentially the makeup, of the mysterious dark matter that pervades the Universe. As part of this project, the team will launch a new astronomy-oriented outreach program at SMU and will develop a series of interactive pedagogical diagrams for astrophysics and cosmology education, which will be used in ASU online courses. This project will demonstrate that a straightforward adaptation of lensing reconstruction techniques enables searches for a stochastic gravitational wave background across a wide range of frequencies. The team will show how this technique can be applied to CMB or optical or line intensity mapping data at a range of wavelengths and will apply this method to Planck data. A second focus of this project is to extend a newly developed small-scale CMB lensing estimator that does not rely on map-level reconstruction. The team will apply this estimator to observational, utilizing CMB maps from Planck and the Atacama Cosmology Telescope to provide insights into an as-yet unmeasured regime of CMB lensing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.