2 Ancient Galaxies Just Changed Everything We Know About the Universe

Thursday, 07 December 2017 - 12:02PM
Thursday, 07 December 2017 - 12:02PM
2 Ancient Galaxies Just Changed Everything We Know About the Universe
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Image credit: NASA
Astronomers peering deep into space are finding star-packed galaxies in a place they didn't expect, changing everything we thought we knew about the beginning of the universe. 
Current thinking holds that the first galaxies, forming a few hundred million years following the Big Bang, would be more like today's dwarf galaxies, smaller collections of stars that are companions to larger galaxies, holding only a mere, few billion stars—perhaps eventually coalescing into bigger galaxies.

However, observations at the Atacama Large Millimeter/submillimeter Array (ALMA) are turning up massive star-studded galaxies in space that science considers to be a section of the cosmos that is less than a billion years of age. 
The focus of this discovery is hinging on the finding of two giant galaxies located in a sector of space determined to be a mere 780 million years old, when our universe was only approximately five percent of its current age.

The galaxies are one point of interest, but even stranger is the structure that houses—yes, envelopes these clusters—a wrap of dark matter that outclasses our Sun by several trillion times.

The two galaxies lie closely within this matter, at a distance shorter than that between the Earth and the center of our galaxy; the two will eventually merge to form the largest galaxy ever observed to exist at its point in the history of the universe.
"With these exquisite ALMA observations, astronomers are seeing the most massive galaxy known in the first billion years of the universe in the process of assembling itself," said Dan Marrone, lead author and University of Arizona associate professor.

We usually view that as the time of little galaxies working hard to chew away at the neutral intergalactic medium…Mounting observational evidence with ALMA, however, has helped to reshape that story and continues to push back the time at which truly massive galaxies first emerged in the universe."
2 Ancient Galaxies Just Changed Everything We Know About the Universe