Astronomers may finally have laid eyes on a population of enormous but elusive galaxies in the early universe.
These hefty, star-forming galaxies are shrouded in dust, which hid them from previous searches that used starlight. Now observations of radiation emitted by that interstellar dust have revealed dozens of massive, active galaxies from when the universe was younger than 2 billion years, researchers report online August 7 in Nature. These galaxies may be the long-sought precursors to heavyweight galaxies seen later in the universe’s history, as well as the most massive galaxies around today.
“Discovering massive galaxies at such early times is very exciting,” says Christina Williams, an astronomer at the University of Arizona in Tucson not involved in the work.
Big, inactive galaxies have been found dating back to a couple billion years after the Big Bang. But the formation of those gentle giants has remained mysterious. That’s because astronomers expect such massive, inactive galaxies to originate from big, star-forming powerhouses, and surveys of the earliest cosmos hadn’t uncovered a population of such star-forming progenitor galaxies. [Continue reading…]