Posted on 01/09/2008 1:58:38 PM PST by blam
Mysterious Explosion Detected In The Distant Past, Halfway Back To Big Bang
Nobody knows how the short gamma-ray burst GRB 070714B was triggered, but a leading possibility is the in-spiral and merger of two neutron stars, depicted in this artist rendition. (Credit: NASA/Dana Berry)
ScienceDaily (Jan. 9, 2008) — Using the powerful one-two combo of NASA’s Swift satellite and the Gemini Observatory, astronomers have detected a mysterious type of cosmic explosion farther back in time than ever before. The explosion, known as a short gamma-ray burst (GRB), took place 7.4 billion years ago, more than halfway back to the Big Bang.
"This discovery dramatically moves back the time at which we know short GRBs were exploding. The short burst is almost twice as far as the previous confirmed record holder," says John Graham of the Johns Hopkins University, in Baltimore, Md.
GRBs are among the most powerful explosions in the universe, releasing enormous amounts of energy in the form of X-rays and gamma rays. Most bursts fall in one of two categories: long bursts and short bursts, depending on whether they last longer or shorter than three seconds. Astronomers think that long GRBs are triggered by the collapse and explosion of massive stars. In contrast, a variety of mechanisms have been proposed for short bursts. The most popular model says that most short GRBs occur when two neutron stars smash into each other and collapse into a black hole, ejecting energy in two counterflowing beams.
The record-setting short burst is known as GRB 070714B, since it was the second GRB detected on July 14, 2007. Swift discovered the GRB in the constellation Taurus. The burst’s high energy and 3-second duration firmly place it in the short GRB category. Rapid follow-up observations with the 2-meter Liverpool Telescope and the 4-meter William Herschel Telescope found an optical afterglow in the same location as the burst, which allowed astronomers to identify the GRB’s host galaxy.
Next, Graham and his colleagues, Andrew Fruchter of the Space Telescope Science Institute, in Baltimore, and Andrew Levan of the University of Warwick, U.K., trained the 8-meter Gemini North Telescope in Hawaii on the galaxy. It revealed that the host galaxy has a spectral line from ionized oxygen. The amount that line was shifted toward the red end of the spectrum yields a redshift of 0.92. A redshift of 0.92 translates to a distance of 7.4 billion light-years, meaning the explosion occurred 7.4 billion years ago.
"The fact that this short burst is so far away means this subclass has a broad range of distances, although they still tend to be closer on average than long GRBs," says Swift lead scientist Neil Gehrels of NASA’s Goddard Space Flight Center in Greenbelt, Md.
Gehrels adds that GRB 070714B’s energy is about 100 times higher than average for short bursts, and is more similar to the typical energy of a long GRB. "It is unclear whether another mechanism is needed to explain this explosion, such as a neutron star-black hole merger. Or it could be that there are a wide range of energies for neutron star-neutron star mergers, but that seems unlikely."
Another possibility is that GRB 070714B concentrated its energy in two very narrow beams, and one of the beams happened to be aimed directly at Earth. This would make the burst seem more powerful than it really was. Perhaps most short GRBs eject their energy in wider and less-concentrated beams.
"We now have a good idea of the type of star that produces the brighter long bursts. But how short bursts are formed remains a mystery," says Fruchter.
Swift is managed by NASA Goddard and was built and is operated in collaboration with Penn State University, the Los Alamos National Laboratory, and General Dynamics in the U.S.; the University of Leicester and Mullard Space Sciences Laboratory in the U.K.; Brera Observatory and the Italian Space Agency in Italy; plus partners in Germany and Japan.
John Graham is presenting his group’s discovery January 7 in a poster at the American Astronomical Society’s 2008 winter meeting in Austin, Texas.
Adapted from materials provided by NASA/Goddard Space Flight Center.
The medium bang?
Folks sure had short fuses back in the day...
Early Taco Bell?
The Bantam Bang?
The Big Bang's echo bouncing off the table in God's kitchen
bkmarking for tonight. Thanks blam.
Is this in the Bible? Must be in the back , by the football betting exemption .
Wow, if you were on a planet in that neighborhood, this thing could seriously ruin your day.
Helen Thomas + Lentils.
Is Kolob in that neighborhood?
The History Channel has a thing on GRB’s. According to that program the big one’s are caused by massive, short-lived stars going “hyper-nova”, mainly to be found in young galaxies made up of such stars.
It’s the small version—the binary Neutron stars merging—that happen in galaxies like the Milky Way and which present more of a threat to us.
The program implicated such a blast, nearby, in the Ordovician mass extinctions.
-- Marvin
I don’t think we’ll be able to find out until we invent the warp drive and build the Enterprise. :-))
Halfway back to the ‘Big Bang’?
I must have missed something. Somebody please tell me when the ‘Big Bang THEORY’ ceased being a THEORY and has been found to be FACT.
I must have been out sick that day.
Bush’s fault?
I'm still totally flabbergasted that they can see an optical "afterglow" INSIDE a galaxy that's 7.4 billion light years away! I'll bet that if we were only a thousand lys away from it, we wouldn't be describing it as an afterglow, but as a hell cauldron that was melting our eyeballs out and blasting the flesh off our bones. I know that if you are directly in one of the jets and anywhere close to the action, it's curtains for you. But these afterglows sound pretty awesome as well.
It was Marvin.
bump
Heard some sirens and saw some flashes of light in the southern sky in my back yard about an hour ago. What’s going on?
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