There is “something new and interesting going on in the universe,” said Alan Kogut of NASA’s Goddard Space Flight Center in Greenbelt, Md.
A team led by Kogut detected the signal with a balloon-borne instrument named ARCADE (Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission).
In July 2006, the instrument was launched from NASA’s Columbia Scientific Balloon Facility in Palestine, Texas, and reached an altitude of about 120,000 feet (36,500 meters), where the atmosphere thins into the vacuum of space.
ARCADE’s mission was to search the sky for faint signs of heat from the first generation of stars, but instead they heard a roar from the distant reaches of the universe.
“The universe really threw us a curve,” Kogut said. “Instead of the faint signal we hoped to find, here was this booming noise six times louder than anyone had predicted.”
Detailed analysis of the signal ruled out primordial stars or any known radio sources, including gas in the outermost halo of our own galaxy.
Other radio galaxies also can’t account for the noise – there just aren’t enough of them.
“You’d have to pack them into the universe like sardines,” said study team member Dale Fixsen of the University of Maryland. “There wouldn’t be any space left between one galaxy and the next.”
The signal is measured to be six times brighter than the combined emission of all known radio sources in the universe.
For now, the origin of the signal remains a mystery.
Read it all here.