Hidden Galaxies Revealed (Sky & Telescope)
Hidden Galaxies Revealed
By: Monica Young | March 24, 2016
Astronomers studying the infrared glow that pervades the universe have pinned down its source: dusty, faint, and faraway galaxies.
If you’re ever fortunate enough to see the Milky Way in a dark sky, take a moment to gaze at that dim glow that emanates from our galaxy’s billions of stars. They’re much too faint and faraway for our eyes to make them out so they blend into a fuzzy patch of light. It takes powerful telescopes to separate out the stellar Tom, Dick and Harrys in the galactic center, for example.
A similar challenge presents itself in the infrared sky. Astronomers have long puzzled over a faint thermal glow that pervades the universe, the so-called cosmic infrared background. Until recently, though, telescopes have lacked the sensitivity to find its source.
Enter ALMA. The Atacama Large Millimeter/submillimeter Array consists of 66 radio dishes working together high in the Chilean desert, collecting submillimeter-wavelength radiation with unprecedented sensitivity. So when Seiji Fujimoto (University of Tokyo, Japan) and colleagues pored through ALMA observations, they saw not a vague background glow but more than a hundred tiny, dusty galaxies. The astronomers have published their results in the Astrophysical Journal Supplement.
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