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LONDON
(AP) — A group of researchers claim they’ve found the most distant
explosion ever detected, a pulse of high energy radiation sent by a
disintegrating star near the very edge of the observable universe.
The
stellar blast was first spotted by a NASA satellite in April 2009, but
researchers announced Wednesday that they have since gathered data
placing it more than 13 billion light years away — meaning that the
event took place when the universe was still in its infancy.
Andrew
Levan, one of the scientists behind the discovery, said this blast from
the past blew open a window onto the universe’s early years, showing
that massive stars were already dying within the first few hundred
million years of the birth of the universe.
This
particular explosion wasn’t a supernova but a gamma ray burst, the name
given to a short but powerful pulse of high energy radiation. Such
bursts, thought to result from the collapse of massive stars into black
holes, shoot jets of energy across the universe.
Charles
Meegan, a researcher in gamma ray astronomy, said that a typical burst
“puts out in a few seconds the same energy expended the sun in its whole
10 billion year life span.”
“You can’t get your arms around that very easily,” he said. “I can’t. And I’ve been thinking about it for decades.”
Not
only are gamma ray bursts more powerful than supernovae, they’re faster
too — typically lasting only a few seconds or minutes. They work
differently as well. Whereas a supernova spreads its radiation all
around, gamma ray bursts shoot it out in narrow beams, like a laser,
which can make them hard to detect.
NASA’s
Neil Gehrels, who serves as the lead scientist on Swift, the gamma-ray
detecting satellite which first picked the distant burst’s signal, said
that “we only see about one in 1,000 of all the gamma ray bursts that go
off.”
So when a promising one comes along, scientists take note.
Levan
said he was at an early morning meeting in Sweden on April 29, 2009,
when his phone went off, alerting him to the explosion. From that moment
on, it was a race against time. Gamma ray bursts come and go far too
quickly for telescopes, but their afterglows linger for a little while
longer and can be analyzed by astronomers.
Levan rushed out of the meeting.
“Fortunately the office was next door,” he said. “So I was able to rush into the building and get online.”
There
Levan got a little less lucky. Some of the world’s most powerful
telescopes were soon tasked with tracking the burst, but the view from
Chile’s La Silla Observatory was hampered by unfavorable atmospheric
conditions, while two Hawaiian telescopes — Gemini North and the United
Kingdom Infrared Telescope — were buffeted by high winds. Chile’s Very
Large Telescope managed to train its eye on the sky for a while, but by
then it was already getting light.
An undated photo released Thursday May 26, 2011 by the University of Warwick of astronomer Dr. Andrew Levan who was one of the first members of the team to spot an exploding star. A group of researchers claim they’ve found the most distant explosion ever detected, a pulse of gamma radiation sent by a disintegrating star more than 13 billion light years away. The stellar blast was first sniffed out by a NASA satellite in April 2009, but researchers announced Wednesday that they’ve since gathered data placing it near the very edge of the observable universe. The explosion identified by the scientists wasn’t a supernova but a gamma ray burst, the name given to a short but powerful pulse of high energy radiation. Such bursts are thought to result from the collapse of massive stars into black holes, and the amount of energy they release is mind-boggling. (AP Photo/HO University of Warwick) |
The
glitches deprived Levan’s team of some important data, but they spent
the next two years painstakingly trying to build context and
double-check their observations. His paper, due to published soon in
Astrophysical Journal, stated with 90 percent certainty that the gamma
ray burst had been spotted between 13.11 billion and 13.16 billion light
years away.
Gehrels,
whose satellite identified the burst but who wasn’t involved in drawing
up the paper, said he believed Levan was right — praising his team’s
“careful analysis.”
But
other outside experts said they were skeptical. Richard Ellis, a
professor of astronomy at the California Institute of Technology, called
the discovery “potentially very exciting” but said that there wasn’t
enough data to justify such a bullish estimate. In any case, he warned
of the difficulties associated with peering across such a vast distance.
“This is plonk at the frontier, where we have very little idea what’s going on,” he said.
Richard
McMahon, a professor of astronomy at Cambridge University, made a
similar point, pointing out that the mechanics of how gamma ray bursts
occurred were still too little understood to rule out the possibility
that some other factor could be at play.
“There are still some surprises in store for us,” he predicted.
Levan
teaches astronomy at England’s University of Warwick. The paper’s lead
author, Antonio Cucchiara, is at University of California, Berkeley. The
paper counts 31 other co-authors.
Extensive coverage of discovery at Penn State
SOURCE: The Associated Press
