Astronomers have observed a dramatic collision between two galaxies over 11 billion light-years away, a period when the universe was only 18% of its current age. This event, dubbed a "cosmic joust," showcases how a quasar, powered by a supermassive black hole in one galaxy, can disrupt star formation in a neighboring galaxy.
The quasar emits intense radiation that pierces through the colliding galaxy, fragmenting the gas clouds necessary for star birth into smaller, denser clumps. These clumps are too small to effectively form stars, essentially shutting down star formation in the affected galaxy. This observation, made using the Very Large Telescope (VLT) and the Atacama Large Millimeter/submillimeter Array (ALMA), confirms long-standing theories about the influence of quasars on galaxy evolution.
The merger also provides the black hole with more fuel, sustaining the quasar's activity and its disruptive effects. This discovery, published in *Nature* on May 21, 2025, offers valuable insights into the dynamic processes shaping galaxies in the early universe.