According to Quantum FFF Theory, black holes (BHs) do not emit gravitons they eat the local vacuum, resulting in a sort of Casimir gravity effect. As a consrquence, black holes have NO INERTIAL MASS!
This idea is supported by the fast orbit rotation of both LIGO BHs.
Two black holes in line with each other produce so called lighthouse vacuum gravity effects. Just like the opposite of a rotating Lawn sprinkler effect spitting water packets around.
The black holes however are pitting diluted vacuum packets around with the speed of light creating so called macroscopic Casimir cavities effecting all objects with a direct hit, even the mirrors in the LIGO system.
Inertial mass is supposed to be created only by Fermions.
Spinning propeller particles are needed to change Higgs field particles into photons like gravitons.
The nucleus of a black hole is supposed to be a massive stiff Quantum Knot.of multiple mainly photonic particles compressed together by the infalling oscillating Higgsfield (dark energy).
Below: Black hole merger LIGO strain data cleaned from background noise. Made by Nicholas Lincoln.
see also the flash: https://vimeo.com/155170141
With a short gamma ray burst (GRB)