Fixed on one small patch of sky for more than 50 hours, the Very Large Array telescope near Socorro, N.M., determined about 63 percent of the cosmic background radio emission comes from galaxies with black holes feeding at their centers, and the remaining 37 percent comes from galaxies rapidly forming stars.
While previous studies had measured the amount of radio emission coming from the distant universe, they had not been capable of attributing all the radio waves to specific objects.
"The sensitivity and resolution of the VLA, following its decade-long upgrade, made it possible to identify the specific objects responsible for nearly all of the radio background emission coming from beyond our own Milky Way Galaxy," Jim Condon of the National Radio Astronomy Observatory said in a release Tuesday.
"Before we had this capability, we could not detect the numerous faint sources that produce much of the background emission," he said. "The VLA now is a million times more sensitive than the radio telescopes that made landmark surveys of the sky in the 1960s."