Intensity Interferometry prospects with the CTAO

A resolved optical image of a gamma-ray emitter would be of enormous scientific interest. For gamma-ray sources associated with interacting stars (colliding winds or novae), stellar intensity interferometry (SII), envisioned as a second observing mode at the Cherenkov Telescope Array Observatory (CTAO), could yield images of the systems in visible light. Recent radius measurements of massive stars with the current generation of Cherenkov telescopes demonstrate that SII is practical, but a timely and intensive effort is needed before images of interacting stars are possible. Fortunately there is also much interesting stellar astrophysics to do along the way: simultaneous mass and radius measurements, resolving stellar oscillations, and imaging outflows from stars. This contribution presents a matrix of the challenges and scientific opportunities for SII at the CTAO.