Photons leave their mark in high-energy radiation from powerful galaxies
Light from the universe’s very first stars still lingers in space. Now, astronomers have a new way to catch it: Distant, ultra-bright galaxies that act as cosmic beacons, capturing relict photons in a blaze of gamma rays.
But it’s not just these earliest photons that are snared; photons from every star that ever shone can be captured. “We now have constraints on the total number of stars that ever formed,” Volker Bromm, an astronomer at the University of Texas at Austin, says of the new way to see old light, described online November 1 in Science. “It provides us with a review of the entire