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GRB 080916C
GRB 080916C is a gamma-ray burst (GRB) that was recorded on September 16, 2008 in the Carina constellation and detected by NASA's Fermi Gamma-ray Space Telescope. It is the most powerful gamma-ray burst ever recorded. The explosion had the energy of approximately 5900 type Ia supernovae, and the gas jets emitting the initial gamma rays moved at a minimum velocity of approximately 299,792,158 m/s (0.999999c), making this blast the most extreme recorded to date.〔(Most Extreme Gamma-ray Blast Ever, Seen By Fermi Gamma-ray Space Telescope ), Science Daily, February 19, 2009〕〔(Huge gamma-ray blast spotted 12.2 bln light-years from earth ), AFP, February 19, 2009〕
The energy comparison with a supernova ignores that most of the energy of a supernova is carried away in the neutrino burst. The total isotropic energy of GRB 080916C is estimated at () (the oft quoted 4.9 times the sun’s mass turned to energy) and should be jet-corrected to a much lower actual energy output due to the narrow angular width of the actual bursting jet. Thus it would be significantly less than the energy of a supernova neutrino burst, but is about equal to the energy in a supernova’s material explosion. Also, the peak energy flux of GRB 080916C is significantly less than a number of other GRB’s, such as GRB 080319B which peaked at nearly () in visible light alone. However, the total energy flux of the very long duration GRB 080916C is higher than any other measured GRB to date.
The 16.5-second delay for the highest-energy gamma ray observed in this burst is consistent with some theories of quantum gravity, which state that all forms of light may not travel through space at the same speed. Very-high-energy gamma rays may be slowed down as they propagate through the quantum turbulence of space-time.〔(Most Powerful Gamma-Ray Burst May Point to New Physics ), Sky and Telescope, February 19, 2009〕〔(New telescope finds strange behavior in gamma-ray bursts, and also documents the most energetic burst known ), Science News, February 20, 2009〕
The explosion took place 12.2 billion light-years (light travel distance) away. That means it occurred 12.2 billion years ago—when the universe was only about 1.5 billion years old. The burst lasted for 23 minutes, almost 700 times as long as the two-second average for high energy GRBs. Follow-up observations were made 32 hours after the blast using the Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) on the 2.2 metre telescope at the European Southern Observatory in La Silla, Chile, allowing astronomers to pinpoint the blast’s distance to 12.2 billion light years.〔(Fermi’s record breaking gamma-ray burst ), Astronomy Now, February 20, 2009〕
== References ==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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