Testing General Relativity with the Event Horizon Telescope

Thu, April 02, 2015

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The Event Horizon Telescope will generate the first images of the shadows of the black holes in the Milky Way and in M87. The observed mm photons will have originated in two of the strongest gravitational fields found in the Universe, encoding during their travel to the Earth the properties of the black-hole spacetimes. In this talk, I will discuss the prospect of performing a new tests of General Relativity with Event Horizon Telescope observations of Sgr A* that are free of the complexities related to the accretion flow. I will address a a small number of outstanding questions related to the scattering screen towards the galactic center that need to be answered in order for these tests to be performed. I will then use results from recent GPU-accelerated ray tracing calculations in conjunction with GRMHD simulations to argue that upcoming observations of Sgr A* with the Event Horizon Telescope will be able to confirm the GR predictions for the size and shape of the black-hole shadow to an accuracy of better than 10%, in a model independent way.