Srijit Bhattacharjee (IIIT Allahabad, India)

Asymptotic Symmetries and Memories at Spacetime Boundaries

The asymptotic structure of flat spacetimes is rich due to the presence of an infinite dimensional BMS group at the asymptotic null boundaries. The BMS group encompasses the Lorentz symmetries and infinitely many additional symmetries like supertranslations. Supertranslations play a key role in understanding the relation between soft gravitational scatterings, and memory effects. There have been suggestions that supertranslations like symmetries should also be present near the horizon of a stationary black hole. In this talk, I will discuss some recent developments of the BMS-supertranslations at spacelike, and timelike boundaries of flat spacetimes. Further, I will also discuss the emergence of supertranslation-like symmetries near the horizon of a black hole and their memories.