Source of rare cosmic glow found

MUNICH, Germany, Aug. 17 (UPI) -- Astronomers using a telescope in Chile to observe one of the biggest and brightest objects in the universe say its glow comes from galaxies hidden within.

Researchers used the Very Large Telescope of the European Southern Observatory to study an unusual object known as a Lyman-alpha blob, rare and very luminous structures seen in regions of the early universe where matter is concentrated, a release from observatory headquarters in Munich said Wednesday.

Lyman-alpha blobs are gigantic clouds of hydrogen gas that can span a few hundred thousand light-years, several times larger than our Milky Way galaxy, and are as bright as the brightest galaxies.

But the power source for their extreme luminosity has remained unclear until now. One theory has been that cool hydrogen gas is pulled in by the blob's powerful gravity and heats up.

However, astronomers using the observatory's telescope discovered that light coming from the blob is polarized, an effect almost impossible to produce if light simply comes from the gas in the blob under gravity but just what would be expected if the light originated from galaxies embedded in the central region of the object before being scattered by the gas.

"We have shown for the first time that the glow of this enigmatic object is scattered light from brilliant galaxies hidden within, rather than the gas throughout the cloud itself shining." observatory astronomer Matthew Hayes said.