Special Seminar: The union of next-generation photometric and spectroscopic surveys: Probing large-scale cosmic structure with LSST and DESI-II+4MOST-informed astrophysics

Abstract: With the advent of the largest photometric survey ever undertaken in the Vera Rubin Observatory’s Legacy Survey of Space and Time (LSST) and massively-multiplexed spectroscopic instruments in DESI and 4MOST, we are entering a data-rich regime with incredible statistical potential to shed light on the nature of dark matter and dark energy. Weak gravitational lensing with Rubin will be a powerful probe of large-scale cosmic structure, examining correlations in billions of galaxy shapes after they are minutely distorted through the cosmic web. Cosmological precision from lensing measurements is now limited by our ability to model astrophysical effects—how galaxies intrinsically align with one another, the suppression of structure through explosive baryon feedback, and uncertainty in the relation between galaxy colors and their distances. I will discuss how current and future spectroscopic surveys are uniquely suited to constrain these properties in the next decade and lessons learned from case studies in the Dark Energy Survey. These data-driven, multi-instrument approaches to astrophysical systematics will not only sharpen our picture of galaxy evolution over cosmic time, but also allow the robust use of the smallest cosmic scales – leveraging all our observations to produce the most precise constraints on our cosmological model.