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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