GRB 090423 is the small, very red source in the centre of this image. The red colour is indicative of its great distance - about 13.1 billion light years - since all the optical light has been absorbed by intergalactic hydrogen gas, leaving only infrared light.
Credit: A.J.Levan & N.R.Tanvir
PARIS: It took 13 billion years to reach Earth, but astronomers have seen the light of an exploding mega-star that is the most distant object ever detected, two studies report.
The stunning gamma-ray burst (GRB) was observed by two teams of researchers in April, and opens a window onto a poorly known period when the universe was in its infancy.
GRBs are the most violent explosions known to exist, and can be 10 million times more luminous than the brightest of galaxies.
Catastrophic death
They accompany the catastrophic death of a massive star, and are probably triggered by the collapse of the star's centre into a black hole.
Dubbed GRB 090423, the new discovery was first spotted by the NASA satellite Swift. Astronomers alerted to the find trained several of Earth's largest telescopes skyward just in time to see the gamma-ray burst's fading afterglow.
Both studies ware published this week in the British science journal Nature. The discovery is especially exciting for scientists because the explosion occurred during the so-called 'cosmic dark ages', which started a mere 400,000 years after the Big Bang set the universe in motion some 13.7 billion years ago.
During this period, free electrons and protons combined to form neutral atoms with the same number of positive and negative charges, resulting in an opaque - or 'dark' - universe.
Cosmic dark ages
Not until 800 to 900 million years after the Big Bang were atoms and molecules 're-ionised', or electrically charged, resulting in the relatively transluscent inter-galactic medium we see today.
GRB 090423 flashed and crashed toward the end of these dark ages, making it the oldest object ever seen.
"This observation allows us to begin exploring the last blank space on our map of the Universe," said Nial Tanvir, a professor at the University of Leicester, in England, and lead author of one of the studies.
"It is tremendously exciting to be looking back in time to an era when the first stars were just switching on," added Andrew Levan, a professor at the University of Warwick and co-author of the same study.
The previous record holder for oldest object is at least 150 million years younger than the newly discovered gamma-ray burst.
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Telescopes ?
I have often wondered whether telescopes merely magnify things, or do they look back into time ? Will this same event be visible later, with a lower power scope, or with the naked eye ?
The maximum distance we were
The maximum distance we were from this event when it occurred is 1800m light years if it happened 900m years after the big bang.
If we had stayed where we were, light from the event would take 1,800m years to reach us.
The fact that it has taken 13,000m years surely indicates we must be traveling at least 86% the speed of light away from the origin. (we have traveled 13,000m - 1,800 light years in 13,000m years).
Maybe that is common knowledge, but that makes me feel a little giddy.
Inflation theory
We're not travelling at 86% the speed of light, and there is no origin/center of the universe. Space/time itself expanded equally in all directions. At one time space/time expanded faster than the speed of light.