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Galactic assembly seen in early universe for the first time

"Although this is one of the deepest ALMA observations so far it is still far from achieving its ultimate capabilities," researcher Roberto Maiolino said.
By Brooks Hays   |   July 22, 2015 at 9:20 AM

CAMBRIDGE, Mass., July 22 (UPI) -- For the first time, astronomers in Europe have observed star-forming gas clouds in the early universe -- the building blocks of the first galaxies.

The faint glow of ionized carbon was spotted by the European Southern Observatory's ALMA telescope, located in Chile. To find these earliest galaxies, researchers trained the telescope deep into space, past the obvious light of more mature quasars and star-filled galaxies.

While aiming ALMA's instruments at some of the oldest known galaxies -- formed just 800 million years after the Big Bang -- astronomers picked up the signal of glowing carbon just to the side of one of these ancient galaxies, known as BDF 3299.

"This is the most distant detection ever of this kind of emission from a 'normal' galaxy, seen less than one billion years after the Big Bang," Andrea Ferrara, an astronomer with Italy's Scuola Normale Superiore and co-author of a new study on the findings, said in a press release.

"It gives us the opportunity to watch the build-up of the first galaxies," Ferrara explained. "For the first time we are seeing early galaxies not merely as tiny blobs, but as objects with internal structure!"

In the early universe, space was littered with dusty gas clouds. But as powerful stars burst to life, this gas and dust was cleared out of the way -- a process known as reionization.

Researchers say the glowing gas spotted by ALMA is originating from the outskirts BDF 3299 because it has been cleared out of the center of the galaxy by the energy of newly formed stars. In other words, researchers believe they're witnessing reionization.

"We have been trying to understand the interstellar medium and the formation of the reionisation sources for many years," Ferrara said. "This type of observation will clarify many of the thorny problems we have with the formation of the first stars and galaxies in the Universe."

Study leader Roberto Maiolino, an astronomer with the Cavendish Laboratory and Kavli Institute for Cosmology at the University of Cambridge, said the discovery wouldn't have been possible without ALMA.

"Although this is one of the deepest ALMA observations so far it is still far from achieving its ultimate capabilities," Maiolino said. "In future ALMA will image the fine structure of primordial galaxies and trace in detail the build-up of the very first galaxies."

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