Credit: Hennawi & Arrigoni-Battaia, MPIA

Astronomers have discovered a massive cluster of four quasars — a rare find of galaxies just being born.

Quasars are young, bright galaxies powered by supermassive black holes and are hard to find because this youthful period is brief. Using the W. M. Keck Observatory in Hawaii, Joseph Hennawi of the Max Planck Institute for Astronomy in Heidelberg, Germany, and his colleagues found the quasars (pictured, indicated by arrows) at the heart of one of the largest known nebulae — clouds of gas that, if large enough, can give birth to new galaxies. The quasars are illuminating the surrounding gas and are probably evolving into a massive galaxy cluster.

This rare grouping, together with the size of the nebula, suggests that gas in protogalactic clusters might be cooler and denser than was thought.

Science 348, 779–783 (2015)