What lurks at the very edge of the observable Universe? As it’s so distant, and as the light from any primordial galaxies took so long to get here, by observing any object that far away is to also look back in time.
Now astronomers using the Japanese Subaru and Keck II telescopes — observatories situated atop Mauna Kea, Hawaii — have managed to look deep into the cosmic past revealing one of the most distant objects ever discovered. In fact, only two other objects have been spotted at a greater distance.
As it’s so far away, this particular “blob” existed when the Universe was only a fraction of its current age — when it was only 750 million years old, or 5 percent its current age. (Our Universe is precisely 13.75 billion years old, by the way.)
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The blob in question appears to be a very young galaxy — called GN-108036 — with a surprisingly high star birth rate. It’s birthing around 100 baby stars per year, 30 times the star production rate of our Milky Way.
“We’re really surprised to know that GN-108036 is quite luminous in ultraviolet and harbors a powerful star formation,” said astronomer Yoshiaki Ono of the University of Tokyo, Japan. “We had never seen such a vigorously star-forming galaxy at a comparable distance until the discovery of GN-108036.”
The team’s work is set to be published in The Astrophysical Journal.
Previous surveys didn’t detect the galaxy because of its high star formation rate; it wasn’t thought that (before the discovery of GN-108036) the earliest galaxies in the history of the Universe were so active.
“Perhaps those surveys were just too small to find galaxies like GN-108036,” said Mark Dickinson of the National Optical Astronomy Observatory in Tucson, Ariz. “It may be a special, rare object that we just happened to catch during an extreme burst of star formation.”
This young galaxy is interesting as it emerged soon after the “dark ages” of our Universe. This cosmic epoch would have been especially depressing as our entire Universe was choked with thick clouds of hydrogen. No light could traverse space without getting absorbed — it was the epitome of a cosmos-wide pea soup fog.
Only when the earliest galaxies began to form, with throbbing black holes in their cores, was this opaque cosmic soup “burned away” by the ionizing radiation generated by quasars.
It is thought that galaxies like GN-108036 were the first to emerge from the dark ages after helping to blast the fog away.
“The high rate of star formation found for GN-108036 implies that it was rapidly building up its mass some 750 million years after the Big Bang, when the universe was only five percent of its present age,” said Bahram Mobasher, of the University of California, Riverside. “This was therefore a likely ancestor of massive and evolved galaxies seen today.”
For more information on this fascinating discovery, read the Keck Observatory press release. The Subaru press release can be found here.
Image: The location of GN-108036 in Hubble and Spitzer space telescope images. Credit: NASA / JPL-Caltech / STScI-ESA / Y. Ono (Univ. of Tokyo) and B. Weiner (Univ. of Arizona)