Superdilations at Schwarzschild null infinity

Abstract

Relying on the definition of asymptotic conformal Killing horizons, the generators of asymptotic conformal symmetries at future null infinity in Schwarzschild space-time are considered. The algebra they close is an extended version of the BMS one due to the emergence of superdilations. Several features are then studied, such as the related non-trivial charge, ruling out the hypothesis that superdilations are pure gauge transformations. Their effect on a pair of celestial observers can be understood as an angle-dependent redshift, connected to the local non-vanishing flux of the charge.