Once a gamma-ray burst is detected from space, other telescopes take a look. Here, the fading infrared afterglow of GRB 090423 appears in the center of this false-color image taken with the Gemini North Telescope in Hawaii. The burst is the farthest cosmic explosion yet seen.
Credit: Gemini Observatory/NSF/AURA, D. Fox and A. Cucchiara (Penn State Univ.) and E. Berger (Harvard Univ.)
A stellar explosion has smashed the record for most distant object in the known universe.
The gamma-ray burst came from about 13 billion light-years away, and represents a relic from when the universe was just 630 million years old.
"It easily surpassed the most distant galaxies and quasars," said Edo Berger, an astrophysicist at Harvard University and a leading member of the team that first demonstrated the burst's origin. "In fact, it showed that we can use these spectacular events to pinpoint the first generation of stars and galaxies."
"The burst most likely arose from the explosion of a massive star," said Derek Fox, an astrophysicist at Penn State University. "We're seeing the demise of a star and probably the birth of a black hole in one of the universe's earliest stellar generations."
Gamma-ray bursts mark the dying explosion of large stars that have run out of fuel. The collapsing star cores form either black holes or neutron stars that create an intense burst of high-energy gamma-rays and form some of the brightest explosions in the early universe.
A light-year is the distance that light can travel in a year, or about 6 trillion miles (10 trillion kilometers). So astronomers are seeing this particular burst as it existed 13 billion years ago, because the light took that long to reach Earth observers.
NASA's Swift satellite first detected the ten-second-long gamma-ray burst in the early morning on April 23, and quickly swung about to point its Ultraviolet/Optical and X-Ray telescopes.
The satellite found a fading X-ray afterglow, but no visible light. That alone suggests a very distant object, Berger explained, because the ongoing expansion of the universe eventually stretches all visible light into longer infrared wavelengths.
Astronomers from Europe and the U.S. quickly scrambled to follow up on the stunning discovery. They found that the infrared light of the afterglow had the highest redshift ever measured, meaning that the wavelengths had been very stretched out during their long journey.
The Swift satellite had previously made similar record-breaking discoveries, such as a gamma-ray burst detected in September 2008. That burst came from an exploding star 12.8 billion light-years away.
Swift's new find may indicate an active early universe, even as scientists still try to understand what existed so close to the start of it all.
"We now have the first direct proof that the young universe was teeming with exploding stars and newly-born black holes only a few hundred million years after the Big Bang," Berger said.
Last week's announcement of a giant mystery blob discovered near the dawn of time suggests that even larger objects such as galaxies may have also been forming, when the universe was just 800 million years old.
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