| Abstract: |
Adopting geometric-optics approximations in black hole spacetimes enables the identification of a mapping between black hole images and eikonal black hole quasinormal modes (QNMs). More explicitly, the real part and imaginary part of the QNM frequencies correspond to the ring size and the detailed ring structure of the image, respectively, although the explicit identification of such eikonal correspondence relies a lot on the spacetime symmetries and is, in general, non-trivial. In this talk, I will discuss how joining the observations of ringdown and images of black holes could test such correspondence and constrain a class of non-GR theories where such correspondence is broken, opening a novel window of testing gravity. |
