A NASA sounding rocket - a name sometimes given to research rockets - found an unexpected amount of infrared light in the dark space between galaxies.
The light is as bright as every known galaxy combined, and is believed to originate from orphaned stars that were "flung" out of their home galaxies. The findings could redefine what scientists classify as galaxies; which could instead of being a set boundary of stars could be interconnected.
"We think stars are being scattered out into space during galaxy collisions," said Michael Zemcov, lead author of a new paper describing the results from the rocket project and an astronomer at the California Institute of Technology (Caltech) and NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "While we have previously observed cases where stars are flung from galaxies in a tidal stream, our new measurement implies this process is widespread."
The team used suborbital sounding rockets, as part of the Cosmic Infrared Background Experiment (CIBER), to capture wide-field pictures of the cosmic infrared background at two infrared wavelengths shorter than those seen by the Spitzer telescope.
"It is wonderfully exciting for such a small NASA rocket to make such a huge discovery," said Mike Garcia, program scientist from NASA headquarters. "Sounding rockets are an important element in our balanced toolbox of missions from small to large."
The cameras snap pictures for about seven minutes once launched into space and transmit the images back down to Earth. The team rules out light coming from bright stars and galaxies as well as local sources, and found an exorbitant amount of light was still left over.
The new map shows the fluctuations in the remaining infrared background light and contains splotches much larger than individual galaxies. The brightness of these fluctuations allows researchers to measure the total amount of background light.
The researchers were surprised to see the maps revealed an excess of light. They found this light has a blue spectrum, meaning it increases in brightness at shorter wavelengths. The light's properties suggest it comes from a previously unknown population of stars that wander between galaxies.
"The light looks too bright and too blue to be coming from the first generation of galaxies," said James Bock, principal investigator of the CIBER project from Caltech and JPL. "The simplest explanation, which best explains the measurements, is that many stars have been ripped from their galactic birthplace, and that the stripped stars emit on average about as much light as the galaxies themselves."
In the future the researchers hope to confirm that this light is coming from wandering stars.
