Modified Gravity Black Holes and their Observable Shadows

The shadows cast by non-rotating and rotating modified gravity (MOG) black holes are determined by the two parameters mass $M$ and angular momentum $J=Ma$. The sizes of the shadows cast by the spherically symmetric static Schwarzschild-MOG and Kerr-MOG rotating black holes increase significantly as the free parameter $\alpha$ is increased from zero. The Event Horizon Telescope (EHT) shadow image measurements can determine whether Einstein’s general relativity is correct or whether it should be modified in the presence of strong gravitational fields.