First quasar quartet discovered

A foursome of quasars on the far side of the universe heralds the birth of a massive cluster of galaxies, researchers suggest in the May 15 Science. The light from the four blazing cores of galaxies illuminates an enormous hydrogen cloud, 1 million light-years long with the mass of 100 billion suns. The cloud might be fueling the fledgling cluster, which is seen as it was roughly 3 billion years after the Big Bang.

Astronomers have found quasars living alone, in pairs and even as triplets. But this is the first time four have been seen snuggled up to one another. Since quasars are thought to switch on when galaxies collide, the troupe probably lives in a crowded neighborhood where galaxies routinely bump into one another, suggest cosmologist Joseph Hennawi of the Max Planck Institute for Astronomy in Heidelberg, Germany and colleagues. The quasars and the surrounding gas are also moving around one another quite quickly, implying that strong gravitational forces thread through the cluster.