Galaxy 700 million years after Big Bang

24 October 2013
Posted by Chris Smith.

The most distant galaxy yet discovered - and dating from just 700 million years after the Big Bang - has been pinpointed by scientists in the Artistic impression of gas accretion on a high redshift galaxy.US.

Dubbed z8_GND_5296, the distant star cluster, spotted by University of Texas at Austin astronomer Steven Finkelstein and published this week in Nature, dates back over 13 billion years and gives space scientists their earliest glimpse yet of the young Universe.

The team made the discovery by initially scrutinising approximately 100,000 galaxies documented by the Hubble Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), which used more than a month of Hubble observing time.

Owing to the expansion of the Universe, light coming from more distant objects appears more red, a phenomenon known as red-shifting; so the team used the colours of the observed galaxies to select potential candidates for closer inspection with the Keck Observatory's Keck I telescope in Hawaii.

This has been fitted with a new instrument called MOSFIRE, which can see infrared light, enabling very distant, highly red-shifted galaxies to be observed.

Out of this analysis came z8_GND_5296, with a clear infrared signature for hydrogen - known as the Lyman-alpha spectrum - placing it at just 700 million years after the Big Bang.

However, the team were surprised to find only this one galaxy in their analysis. They think this is because this time point sits on the cusp of a transition in the early Universe when swathes of neutral - opaque - hydrogen gas became ionised by stars, causing the fog to clear.

Remarkably, the analysis also shows that z8_GND_5296 was producing new stars at a rate 150 times greater than our own galaxy.

This study is important because data from galaxies like z8_GND_5296 give astronomers insights into the structure and behaviour of the early Universe, helping them to create more accurate simulations that can be used to model the evolution of the Universe and answer questions such as how our own galaxy, the Milky Way, came to be.

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