Black hole multipoles in higher-derivative gravity

A bstract We consider a broad family of higher-derivative extensions four-dimensional Einstein gravity and study the multipole moments rotating black holes therein. carefully show that various definitions multipoles carry over from general relativity, compute these for Kerr using ACMC expansion formalism. obtain mass M n current S as series expansions in dimensionless spin; some cases we are able to resum into closed-form expressions. Moreover, observe existence intriguing relations between corrections parity-odd 2 ≠ 0 +1 break equatorial symmetry, parity-preserving only modify . Further, comment on ratios Kerr, discuss phenomenological implications future gravitational wave experiments.