Astronomers have potentially uncovered a hidden population of galaxies suffused in far-infrared light. This discovery stems from analyzing unique data from the European Space Agency's Herschel Space Observatory. These galaxies could explain the excess far-infrared light in the universe.
Far-infrared light is emitted by cosmic dust that absorbs starlight. This dust is produced during star formation and death cycles. The more intense this cycle, the more dust is produced, potentially hiding stars within galaxies.
Chris Pearson, an astronomer at the U.K.'s Rutherford Appleton Laboratory, led a team using archival Herschel data. They searched for these missing pieces in the cosmic infrared background. Herschel, which operated until 2013, could view the universe in long wavelengths of far-infrared light.
The team stacked 141 images from Herschel's SPIRE instrument, combined with data from NASA's Spitzer Space Telescope. This created the deepest far-infrared view of the cosmos ever made. They identified 1,848 sources of far-infrared emission in this "dark field".
Statistical analysis suggests these sources are dusty, star-forming dwarf galaxies at varying distances. These galaxies are faint and hard to find, indicating they are smaller galaxies undergoing initial bursts of star formation. Extrapolating these findings suggests a significant contribution to the far-infrared background.
More data is needed to confirm the existence of these hidden galaxies. Pearson's team plans to use the Submillimeter Array (SMA) in Hawaii. A proposed NASA mission called PRIMA, specializing in spectroscopy, could also be instrumental in solving this mystery.
Two papers detailing these findings were published in the journal Monthly Notices of the Royal Astronomical Society.