Constraining GR alternatives with astrophysical probes
Determine whether astrophysical observations can significantly reduce the viable theory space of alternatives to General Relativity, including whether ringdown observations will be sufficiently precise to distinguish quasinormal modes of GR from those of alternative theories and whether environmental effects can be disentangled from genuine deviations.
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Open questions: Will it be possible to significantly shrink the "theory space" of GR alternatives with astrophysical probes? Will future observations of the ringdown phase of black hole mergers be sufficiently precise to distinguish GR quasinormal modes from those of alternative theories? Will we be able to disentangle deviations from GR from environmental effects in astrophysical observations?
A crucial next step will be to extend the analysis to gravitational perturbations, which couple more directly to potential gravitational wave observations; assessing whether the rotating charged regular black holes can be observationally distinguished from one another and from the classical Kerr/Kerr--Newman black hole, given realistic future detector sensitivities.