Black Hole Science Opportunities With Radio Interferometry

by Alex Lupsasca (Vanderbilt University)

Wednesday 17 Sept 2025, 14:00 → 15:00 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

The first Event Horizon Telescope images of the supermassive black hole M87* display a bright ring encircling the event horizon, which appears as a dark patch in its surrounding emission. But Einstein's theory of general relativity predicts that within these images there also lies a thin “photon ring” of light that orbited the black hole before escaping its gravity, carrying information about its spacetime properties and, in particular, its spin. I will describe a NASA Small Explorers Mission being proposed next year: the Black Hole Explorer. BHEX will use space-ground interferometry to create a telescope larger than the Earth and produce the sharpest images in the history of astronomy. By resolving the photon ring, these images will address fundamental questions in black hole physics, including what a black hole looks like, and how fast the black hole Sgr A* at the center of our own galaxy is spinning. BHEX will also target dozens of additional supermassive black holes and measure the magnetic fields suspected to generate their relativistic jets, shedding new light on the mechanism that powers the brightest and most efficient engines in the universe.

Recording