At the heart of every galaxy lies one of the most mysterious objects in the universe: a supermassive black hole. Millions to billions of times the mass of our sun, these giants power astrophysical jets, one of the most energetic processes known to physics. Read the full article at Quanta Magazine: https://www.quantamagazine.org/physicists-identify-the-engine-powering-black-hole-energy-beams-20210520/ Now, through the work of the black hole-observing Event Horizon Telescope (EHT) team, the mystery of what's powering these jets has started to unravel. Several weeks ago, the EHT released its second-ever photo of a black hole — another view of the same fiery ring pitted by darkness seen in 2019. Both images show the glowing plasma around the supermassive black hole at the center of the galaxy M87, whose giant jet rises outside the frame. Unlike in the first photo, the ring in the new image has stripes, indicating that the light is strongly polarized. Experts say the spiral pattern of the stripes results from a strong, orderly magnetic field around the M87 black hole, and that this represents the first significant empirical evidence in favor of a popular 44-year-old theory of jet launching, known as the Blandford-Znajek process.