Oldest, farthest known galaxy identified

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Astronomers have identified a galaxy that is not only the oldest in the known universe, but also the farthest away.

The precise size and age of our universe remain two of the most hotly debated questions in physics, and while it is now believed that the cosmos is approximately 13.77 billion years old, we are still discovering new galaxies in the distant reaches of the universe that challenge, not only where the edge of the observable universe is, but also how soon after the Big Bang galaxies first appeared.

This latest example – a galaxy known as GN-z11 – is the oldest and most distant galaxy found to date and existed at a time when the universe was only a few hundred million years old.

Its distance was recently measured using the Keck I telescope in Hawaii by Professor Nobunari Kashikawa and colleagues from the Department of Astronomy at the University of Tokyo.

“From previous studies, the galaxy GN-z11 seems to be the farthest detectable galaxy from us, at 13.4 billion light years, or 134 nonillion kilometers (that’s 134 followed by 30 zeros),” he said.

“But measuring and verifying such a distance is not an easy task.”

“We looked at ultraviolet light specifically, as that is the area of the electromagnetic spectrum we expected to find the redshifted chemical signatures.”

“The Hubble Space Telescope detected the signature multiple times in the spectrum of GN-z11. However, even the Hubble cannot resolve ultraviolet emission lines to the degree we needed.”

“So we turned to a more up-to-date ground-based spectrograph, an instrument to measure emission lines, called MOSFIRE, which is mounted to the Keck I telescope in Hawaii.”

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