Stronger weak lensing cosmology

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Cosmologists have determined that 95% of the mass and energy in the Universe is "dark," meaning that it neither absorbs nor emits its own light. But the gravity of "dark matter" does bend light, so it is possible to map the dark matter by careful study of the distortions of sky images. Led by the Dark Energy Survey (DES), three large-scale experiments are now measuring distortions using the images of over 100 million galaxies to measure the dark-matter structure of the nearby universe, to see if its growth over time matches the predictions of current theories of gravity, dark matter, and dark energy. To help complete the DES analysis, these researchers will develop new methods for measuring both the distortion of the galaxies and their distances from Earth. The grant also will fund participation of first-generation/low-income undergraduates and the sharing of dark-universe results with the Philadelphia community by travelling exhibits and presentations. Many of the current methods for testing cosmology with imaging surveys like DES and the Rubin Observatory’s Legacy Survey of Space and Time (LSST) are based on ad hoc assumptions and statistics that require complex testing for accuracy and may lose valuable information. This research will replace many of these with methods based on principled statistical representations of the data, rendering the results more understandable, precise, and closer to optimal in extracting information. The PI will also transfer techniques developed for DES calibration to LSST, which will benefit a broad swath of astronomy.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.