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Fermi telescope unveils gamma-ray bursts' highest power side

Washington, Mon, 20 Feb 2012 ANI

Washington, Feb 20 (ANI): The Fermi Gamma-Ray Space Telescope has recorded the ighest energy portion of the gamma-ray bursts, which last for a few seconds.


Detectable for only a few seconds but possessing enormous energy, gamma-ray bursts are ifficult to capture because their energy does not penetrate the Earth's atmosphere.


The Fermi Telescope, formerly called the Gamma-Ray Large Area Space Telescope, was aunched on June 11, 2008. As part of its mission, the telescope records any gamma-ray bursts ithin its viewing area.


"Fermi is lucky to measure the highest energy portion of the gamma-ray burst emission, which ast for hundreds to thousands of seconds maybe 20 minutes," said Peter Meszaros, Eberly hair Professor of Astronomy and Astrophysics and Physics, Penn State.


Most gamma-ray bursts occur when stars that are more than 25 times larger than our sun come o the end of their lives. When the internal nuclear reaction in these stars ends, the star collapses n on itself and forms a black hole. The outer envelope of the star is ejected forming a upernova.


"The black hole is rotating rapidly and as it is swallowing the matter from the star, the rotation jects a jet of material through the supernova envelope," explained Meszaros.


This jet causes the gamma-ray burst, which briefly becomes the brightest thing in the sky. owever, unlike supernovas that radiate in all directions, gamma-ray bursts radiate in a very arrow area, and Fermi sees only jets ejecting in its direction.


This, however, is the direction in which they send their highest energy photons. Any gamma-ray ursts on the other side of the black hole or even off at an angle are invisible to the telescope.


"We actually miss about 500 gamma-ray bursts for every one we detect," Meszaros said.


The gamma-ray bursts that Fermi has seen have allowed astrophysicists to clarify previous heories about gamma-ray bursts.


"We have been able to rule out the simplest version of theories which combine quantum echanics with gravity, although others remain to be tested," said Meszaros


Meszaros noted that Fermi and other programs like the SWIFT telescope have shown that amma-ray bursts last longer than we thought they did and that there are long and short gamma-ay bursts.


Fermi, a more specialized telescope than the SWIFT telescope, which also detects gamma-ray ursts, enabled scientists to look at the very fast near the speed of light jets producing the amma-ray emissions.


While researchers are still modifying scientific theories on the nature of these bursts, thanks to ermi, they now have actual measurements to add to the theoretical debate.


"Fermi has done much better in measuring how close to the speed of light the jet gets. But we till don't know if it is 99.9995 percent the speed of light or 99.99995 percent the speed of ight," said Meszaros.


Gamma-ray bursts occur in many places in the universe, but because they are a product of aging tars they may be able to shed some light on the beginnings of the universe. The bursts are isible at the longest distance from earth and therefore at the earliest time in the universe.


"We think we can detect them at the infancy of the universe," stated Meszaros.


Wherever a gamma-ray burst exists, any planets in the vicinity suffer. Further away, the adiation from a gamma-ray burst would destroy the protective ozone in the upper atmosphere, llowing ultraviolet radiation to kill terrestrial plant life and animals would starve. Only sea life ould remain unharmed. However, it is estimated that such nearby bursts can be expected only very 300 million years.


Because scientists believe that gamma-ray bursts also emit cosmic rays and neutrinos, other bservatories are also observing these phenomena. Ice Cube Neutrino Observatory at the outh Pole is trying to capture neutrinos, while the Pierre Auger Cosmic Ray Observatory in rgentina captures cosmic rays from these objects.


Meszaros presented the finding at the annual meeting of the American Association for the dvancement of Science in Vancouver, British Columbia. (ANI)


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