13bn years ago, the heavens moved

By Steve Connor

The most distant object ever observed in space has provided scientists with an unprecedented insight into the "cosmic dark ages" following the birth of the universe some 13.7 billion years ago.

A gigantic explosion on the edge of the known universe has been confirmed as the furthermost object in the cosmos.

It occurred nearly 700 million years after the Big Bang and its radiation has taken some 13 billion years to reach Earth - making it 13 billion light years away.

The explosion is one of many thousands of gamma-ray bursts that scientists have detected since they were first discovered more than 40 years ago by spy satellites designed to monitor the radiation emitted by man-made nuclear explosions.

This particular gamma-ray burst, named 090423, occurred on April 23 and its afterglow lasted for about 10 seconds before it died out.

This was long enough for the Swift satellite operated by Nasa to identify its location so that other telescopes on the ground could analyse the explosion in more detail.

Gamma-ray bursts are the most energetic events known to scientists. In just a couple of seconds these massively powerful explosions in space release as much energy as the Sun would release in its entire lifecycle of 10 billion years.

Finding a gamma-ray burst that is 13 billion light years away means that it must have taken place within the period known as the "cosmic dark ages", a timespan of about 900 million years that separates the Big Bang from the formation of the earliest stars and galaxies.

"This observation allows us to begin exploring the last blank space on our map of the universe. It's the first time that we've seen an object within this period of the universe's dark ages," said Nial Tanvir, of Leicester University, who led the study published in the journal Nature.

"We're beginning to peer back to the era of the very first structures in the universe. It's the last unexplained era because in broad-brush terms we have a reasonably good idea of what happened during the rest of the life of the universe," he added.

Andrew Levan, of Warwick University, another member of the international research team, said: "We're looking back into the universe when it was very, very young and we're seeing objects that formed in the very early universe - it was one of the first objects to form after the Big Bang.

"These early stars only lived for a few million years. They lived fast and died young," he added.

* The gamma-ray burst 090423 explosion occurred when the universe was less than 5 per cent of its present age and a tenth of its present size.
* The blast occurred nearly 700 million years after the Big Bang, and has taken 13 billion years to reach the earth.


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