Eyes on the invisible: Charting new horizons with the Event Horizon Telescope

The Event Horizon Telescope (EHT) collaboration has captured the first image of a black hole's event horizon in the galaxy M87, and subsequently, in the supermassive black hole at the center of our Milky Way, SgrA*. More recently, the collaboration has released the first follow-up image of M87*, utilizing observations from April 2018. The EHT has also revolutionized our understanding of the relativistic jets commonly present in active galactic nuclei, revealing the processes governing the jet formation, collimation and acceleration with an unprecedented angular resolution.

The upcoming next-generation Event Horizon Telescope (ngEHT) is poised to significantly upgrade the current system by adding new stations and introducing multi-frequency observational capabilities. These will notably improve the ngEHT's angular resolution, dynamic range, and overall coverage.

This expansion is crucial for enabling the ngEHT to create the first movies of black holes, a leap forward in understanding the processes of black hole accretion and the formation of relativistic jets. In addition, the ngEHT's advanced features will be instrumental in exploring alternative theories to General Relativity and will expand our observational reach to include potentially a dozen new black holes.

By adding an orbiting antenna, the Black Hole Explorer (BHEX), a potential NASA mission, will discover and measure the bright and narrow “photon ring” that is predicted to exist in images of black holes, and fully encodes the space-time metric