First Sagittarius A* Event Horizon Telescope Results: The Shadow of the Supermassive Black Hole in the Center of the Milky Way

In 2017 the Event Horizon Telescope (EHT) observed the Galactic Center supermassive black hole Sagittarius A* (Sgr A*), using a global interferometric array of 8 telescopes operating at 1.3mm. I will briefly discuss the prior knowledge of Sgr A* we had going into this project, as well as expectations given comparisons to the first EHT target M87*, and summarize our final results. Our imaging and modeling analyses support an image dominated by a bright, thick ring, consistent with the expectations for a Kerr black hole of mass ~4×10⁶ M_⊙ located at the dynamical center of the Milky Way. Furthermore our models generally favor a lower inclination, a prograde spin and a colder (compared to the ions) population of radiating electrons. Taken together with the earlier EHT results for M87*, we find consistency with the predictions of general relativity now spanning over three orders of magnitude in central mass. Our results also raise important questions that will be investigated via the 2018, 2021 and 2022 EHT campaigns that we are now analyzing.