Legacy Survey of Space and Time

Professor Heidi Wu studies one of the biggest unanswered questions in physics: the nature of dark energy, the mysterious phenomenon associated with the accelerating expansion of the universe.

Wu and her research team are using data from the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST), a 10-year survey of the southern sky designed in part to advance scientists’ understanding of dark energy and dark matter. Her team focuses on galaxy clusters, some of the largest structures in the universe, to investigate how cosmic structure has grown over time. By measuring how the population of galaxy clusters changes across cosmic history, the researchers can test models of cosmic acceleration and place constraints on the properties of dark energy. Wu’s group combines observations with sophisticated computer simulations. The team simulates the distribution of matter, galaxies and galaxy clusters in the universe, then compares those predictions with LSST observations. This approach helps researchers determine which models best explain how the universe has evolved.

LSST began in 2026 and uses the world’s largest digital camera, with 3.2 billion pixels, to repeatedly image the sky over a decade. The resulting data will allow researchers like Wu to trace the evolution of cosmic structure with unprecedented scale and precision.