Astronomers using NASA’s Chandra X-ray Observatory traced the “Treble Clef” — a radio structure that looks like the musical symbol — to a two-stage process in a merging galaxy cluster about 1.55 billion light-years away. First, an outburst from a supermassive black hole drove clouds of charged particles and magnetic fields outward, producing bright radio waves that later faded as the particles lost energy. A later collision between two galaxy clusters then compressed and reenergized that aged plasma, brightening it again in radio light; shock waves from the merger may have helped. The object lies nearly behind the plane of the Milky Way, so X-ray and radio telescopes were needed to see through intervening stars and dust.
