Lijuan Dong

The black hole Swift J1727.8-1613 emits X-ray bursts in a strict rhythm — like a cosmic heart. Gas falling onto the hole forms a spinning disk, and its glow pulsates. A Chinese telescope picked up this rhythm, like a stethoscope catching a heartbeat.

In 2018, something strange happened to the galaxy 1ES 1927+654: its X-ray 'corona'—a cloud of scorching particles around the supermassive black hole — vanished. Over the next few years, it slowly came back. A team of astronomers decided not just to watch the brightness but to listen to the 'tremor' of that glow.