A New Window into Black Holes

Understand

We develop a formalism to compute the gravitational multipole moments and ratios of moments of non-extremal and of supersymmetric black holes in four dimensions, as well as of horizonless microstate geometries of the latter.

• For supersymmetric and for Kerr black holes many of these multipole moments vanish, and their dimensionless ratios are ill-defined.
• We present two methods to compute these dimensionless ratios, which for certain supersymmetric black holes agree spectacularly.
• We also compute these dimensionless ratios for the Kerr solution.