Inferring the charge distribution of black hole events from ringdown data.*

The increasing precision of gravitational wave detectors has enabled even more precise tests of general relativity, including spectroscopic tests of black holes through the measurement of their quasinormal modes (QNMs). These spectroscopic tests ideally compare the QNM frequencies to predictions from theories beyond GR, where black holes may be described by deformations to the standard Kerr metric. We previously presented a framework to compute the leading shifts to QNM frequencies for perturbations around such deformed Kerr black holes, with arbitrary spin. We show the results of that method, applied to the Kerr Newman case and infer posterior distributions over the charge of the remnant of GW150914. In addition, we generalize this to a hierarchical model and infer the population charge distribution of the entire population of gravitational wave events