There is more than meets the eye, at least that’s what a new study from NASA’s Spitzer Space Telescope shows. The infrared light appearing across the sky appears to be from isolated stars that used to be a part of the galaxies. Scientists believe that galaxy merges stripped the stars away from their original locations.
The findings of the study will be published in the journal Nature and are in contrast to the results of another study that used the Spitzer to look at background infrared light; the other study stated that the light results from the first stars and galaxies.
"The infrared background glow in our sky has been a huge mystery," commented the study’s lead author Asantha Cooray, a researcher at the University of California at Irvine, in a prepared statement. "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."
In particular, the group of scientists looked at data pooled from the Bootes field. The field, which is a larger portion of the sky that spans an arc equal to 50 full Earth moons, allowed them to study the pattern of the light on a larger scale.
"We looked at the Bootes field with Spitzer for 250 hours," remarked the study’s co-author Daniel Stern, who works at Jet Propulsion Laboratory, in the statement. "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."
Researchers believe that the light is too bright to be from the first stars and galaxies and they propose that the “blotchy light” seen in Spitzer images are due to "intracluster" or "intrahalo" starlight. The scientists theorize that there is a sprinkling of stars beyond the outer reaches of galaxies and in various spots among clusters of galaxies. One theory states that, when galaxies were growing larger, they hit other galaxies and increased in mass. The galaxies started to tangle gravitationally and, as a result, strips of stars were “shredded” and thrown into space. Another theory states that stray stars are due to galaxies taking over smaller dwarf galaxies.
"A light bulb went off when reading some research papers predicting the existence of diffuse stars," commented Cooray in the statement. "They could explain what we are seeing with Spitzer."
The team of investigators plans to conduct further research to confirm that the stars make up a large part of the background infrared light and NASA's upcoming James Webb Space Telescope (JWST) could be useful in the study.
"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," concluded Eric Smith, JWST's deputy program manager at NASA, in the statement. "The mystery objects making up the background infrared light may finally be exposed."