ASTRONOMY COLLOQUIUM

Explosive growth in digital technology has created a radio interferometry renaissance, enabling current and upcoming astronomical facilities such as ALMA, ngVLA, SKA, and DSA-2000. These same breakthroughs led to the Event Horizon Telescope (EHT), a global very-long-baseline interferometry (VLBI) network operating at 230 GHz that recently produced the first images of black holes. I will summarize our major EHT discoveries,  which have led to new insights in black hole accretion and jet formation. I will also describe ongoing efforts to develop the Black Hole Explorer (BHEX), a mission that will produce the sharpest images in the history of astronomy by extending the EHT to space. Submillimeter space-VLBI will provide access to the bright and narrow "photon ring" that is predicted to exist in images of black holes, produced from light that has orbited the black hole before escaping. In addition to studying the properties of the nearby supermassive black holes M87* and Sgr A*, BHEX will measure the properties of dozens of additional supermassive black holes and will connect them to their relativistic jets, elucidating the power source for the brightest and most efficient engines in the universe.