Soft Black Hole Absorption Rates as Conservation Laws

Understand

The absorption rate of low-energy, or soft, electromagnetic radiation by spherically symmetric black holes in arbitrary dimensions is shown to be fixed by conservation of energy and large gauge transformations.

• We interpret this result as the explicit realization of the Hawking-Perry-Strominger Ward identity for large gauge transformations in the background of a non-evaporating black hole.
• Along the way we rederive and extend previous analytic results regarding the absorption rate for the minimal scalar and the photon.