NASA today announced that the mystery of the blotchy pattern of infrared light seen across the entire sky may finally be solved. According to a new study published in the journal Nature, the light comes from isolated stars that lie beyond the edges of galaxies. The starts are currently thought to have once been a part of galaxies, but were then flung out as the result of chaotic galaxy collisions or mergers.
"The infrared background glow in our sky has been a huge mystery," said Asantha Cooray, lead author of the study and professor of physics and astronomy at the University of California at Irvine. "We have new evidence this light is from the stars that linger between galaxies. Individually, the stars are too faint to be seen, but we think we are seeing their collective glow."
The study looked at data from NASA's Spitzer telescope. Researchers looked at Bootes field, a large portion of the sky covering an arc equivalent to 50 full Earth moons. Data from the Spitzer was recently used to determine a more accurate measurement of the Hubble constant.
"We looked at the Bootes field with Spitzer for 250 hours," said co-author Daniel Stern of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Studying the faint infrared background was one of the core goals of our survey, and we carefully designed the observations in order to directly address the important, challenging question of what causes the background glow."
A previous study, led by Alexander Kashlinsky and published in June of this year, came to a different conclusion on the Spitzer data. That study proposed that the infrared glow comes from the first stars to form in the universe. According to NASA, this new study used less sensitive observations than the Kashlinsky study, but analyzed a larger pattern of the infrared glow due to its larger scale.
Though more research is needed, NASA stated that the new study refutes the early star hypothesis for the infrared glow. It shows that the light pattern of the glow is not consistent with current theories and computer simulations of the first stars and galaxies. NASA's upcoming James Webb Space Telescope (JWST), scheduled to launch sometime around 2018, may be able to confirm the new orphaned star hypothesis.
"The keen infrared vision of the James Webb Telescope will be able to see some of the earliest stars and galaxies directly, as well as the stray stars lurking between the outskirts of nearby galaxies," said Eric Smith, JWST's deputy program manager. "The mystery objects making up the background infrared light may finally be exposed."
(Image courtesy NASA/JPL-Caltech)