M. Petropoulou

At the center of many galaxies lurks a black hole — an object predicted by solutions to the equations of Karl Schwarzschild. Around it stretches a scorching corona — a region of tenuous plasma heated to billions of degrees.

In 2017, the IceCube detector caught a neutrino from the distant galaxy TXS 0506+056. It was like hearing a phone ring from across the ocean: the signal came from where the most energetic particles in the Universe are born. At the same time as the neutrino, astronomers spotted a gamma-ray flare, and two to three years later, radio waves. Why was the radio late?