Study: Distant glowing dust hides several galaxies

The discovery suggests astronomers have been overestimating rates of star formation in distant galaxies.
By Brooks Hays   |   May 6, 2016 at 3:01 PM
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FALMER, England, May 6 (UPI) -- When astronomers spy a distant galaxy surrounded by a wall of glowing dust, they're likely looking at not one but several galaxies.

The revelation was made possible by a new statistical algorithm that can determine which galaxies are illuminating the large blobs of hot gas imaged by Earth-bound observatories.

Researchers detailed the algorithm and its implications in a new paper, set for publication in the journal Monthly Notices of the Royal Astronomical Society.

The task of determining the illumination source of bright intergalactic dust is complicated by two main issues. The first is a resolution problem. Far-infrared scans such as those conducted by the Herschel Space Observatory tend to reveal multiple celestial objects as single entities.

Second, when astronomers take a closer look and see multiple galaxies where there previously appeared to be one, they tend to credit the galaxy closest to the glowing dust and the sole source of light.

The latest statistical model suggests a single galaxy is likely only the source of illumination when it is positioned directly in the center of a gas blob. In all other instances, the analysis suggests, distant glowing gas is being heated by the radiation of several galaxies.

The discovery suggests astronomers have been overestimating rates of star formation in distant galaxies.

"This is a really interesting result because when we assumed that one galaxy had to be responsible for all of the dust emission, it implied that the galaxy must be forming a tremendous number of new stars," lead study author Jillian Scudder, an astrophysicist at the University of Sussex, said in a news release.

"Forming that number of stars in a galaxy so early in the universe is quite hard to explain," Scudder continued. "By finding that each galaxy is actually two or three galaxies, we've dropped the number of stars these galaxies have to be producing by a third."

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