Messages From the Early Universe
Unimaginably distant and powerful, the brief flashes of high-energy radiation known as γ-ray bursts (GRBs) were once one of astronomy’s deepest mysteries. Now they are becoming a penetrating new tool. With orbiting observatories such as NASA’s Fermi and Swift spacecraft routinely spotting the bursts, astronomers are laying plans to use them as cosmic flashbulbs to scrutinize the obscure details of the Universe’s early years.
Seen almost daily, from all directions in space, GRBs are now thought to signal the collapse of a massive star’s core into a black hole, an event that triggers a cataclysmic explosion. Their intense light can shine all the way across the visible Universe — bearing witness to the earliest chapters of its roughly 13-billion-year history. Theorists’ understanding of the flashes is still evolving, but astronomers are discussing how they can use GRBs to chart the chemical evolution of the cosmos as light from the bursts is filtered through gas in the galaxies in which they reside.