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New physics beyond General Relativity can modify image features of blackholes and horizonless spacetimes and increase the separation between photonrings. This motivates us to explore synthetic images consisting of two thinrings. Our synthetic images are parameterized by the separation as well as therelative flux density of the two rings. We perform fits to the visibilityamplitude and analyze closure quantities. The current Event Horizon Telescopearray cannot detect the presence of a second ring in the region of parametersmotivated by particular new-physics cases. We show that this can be improved inthree ways: first, if the array is upgraded with Earth-based telescopes withsufficiently high sensitivity, second, if the array is upgraded with aspace-based station and third, if super-resolution techniques are used for thedata obtained by the array.

Disentangling photon rings beyond General Relativity with future radio-telescope arrays