Cosmic Cannons: Astrophysicists Shed New Light on Black Hole Jets

Black holes are fascinating cosmic entities characterized by gravitational pulls so intense that not even light can escape once it crosses into their event horizons. Yet, intriguingly, more than a hundred years ago, it was discovered that right outside the event horizon, black holes can produce potent streams of matter and energy, referred to as jets, which can travel nearly as fast as light. Telescopic observations have shown these jets extending directly outward in focused streams, resembling laser beams, with some jets reaching lengths that exceed entire galaxies.

Since the discovery of jets, many scholars, including Nobel Laureate Sir Roger Penrose, have studied the formation of these enigmatic phenomena. Currently, two main models attempt to explain jet formation: The “BZ-jet model,” named for the researchers Blandford and Znajek and now the most influential model, posits that a jet is formed by extracting spin energy from a black hole via magnetic field lines connected to the black hole’s event horizon. In contrast, the second model posits that a jet is formed by extracting rotational energy from a black hole’s accretion disk. The latter is a collection of ionized gas rotating around the black hole due to its strong gravitational force. The second model may be described as the “disk-jet model.”