Infrared symmetries on curved spacetimes

Recent progress in the study of gauge and gravitational theories has revealed a deep and surprising interplay between asymptotic symmetries, soft theorems, and memory effects in the infrared regime of asymptotically flat spacetimes. These developments have culminated in the framework of celestial holography, offering a novel approach to flat space holography. A natural next question is how these infrared structures are modified—or whether they persist—when the spacetime background is no longer flat, such as in the presence of a cosmological constant or near other types of asymptotic boundaries, like black hole horizons. This talk will aim to elucidate these recent advances addressing these questions and highlight how these generalized infrared symmetries may leave observable imprints—from gravitational wave memory to potential signatures in the cosmological sky.