Discovered: the galaxy that's so far away we're seeing it as it was 13 billion years ago

Scientists detected z8-GND-5296 with help of Hubble Space Telescope and Keck Telescope in Hawaii

Steve Connor@SteveAConnor
Wednesday 23 October 2013 18:04

Astronomers have detected the furthest known galaxy in the Universe which is more than 13 billion light years away on the very edge of space.

Because of the time it takes for its light to reach Earth, the galaxy is seen today as it was just 700 million years after the Big Bang - the primordial event that created the Universe some 13.8 billion years ago.

Scientists detected the galaxy - known as z8-GND-5296 - with the help of the Hubble Space Telescope parked in geostationary orbit and the Keck Telescope on the summit of Mauna Kea in Hawaii.

They searched a library of about 100,000 of the most distant galaxies before finding that one of them could be accurately positioned in space by analysing the infrared light it had emitted.

A spectroscopic analysis of the galaxy's wavelength showed how much it has shifted to the red end of the spectrum. This "redshift", and the known expansion velocity of the Universe, was used to measure the galaxy's precise distance from Earth.

"What makes this galaxy unique, compare to other such discoveries, is the spectroscopic confirmation of its distance," said Bahran Mobasher of the University of California, Riverside and a member of the research team.

"By observing a galaxy that far back in time, we can study the earliest formation of galaxies. By comparing properties of galaxies at different distances, we can explore the evolution of galaxies throughout the age of the Universe," Dr Mobasher said.

At this particular point in its early history, the z8-GND-5296 galaxy was producing new stars at a rate of about 300 a year, which is about 100 times faster than our own galaxy, the Milky Way.

There is only one other known object to be further away in space - a massive star that had exploded some 70 million years earlier. The period before this is known as the "cosmic dark ages" because so little is known about it.

Astronomers believe they are close to finding the first galaxies that were probably responsible for the transition from an opaque Universe, when much of its hydrogen was neutral, to a translucent Universe, when the hydrogen became ionised - called the Era of Re-ionisation.

Steven Finkelstein of the University of Texas at Austin, who led the project, said the new galaxy is in the same region of the sky as the previous record holder.

"So we're learning something about the distant universe. There are way more regions of very high star formation than we previously thought. There must be a decent number of them if we happen to find two in the same area of the sky," Dr Finkelstein said.

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