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Fermi Telescope Probes "Dragons" of the Gamma-ray Sky
Happy Anniversary, Fermi Telescope
Noontime Concert Tomorrow: Tokai String Quartet
Wednesday - March 3, 2010 |
Fermi Telescope Probes "Dragons" of the Gamma-ray SkyOne of the pleasures of perusing ancient maps is locating regions so poorly explored that mapmakers warned of dragons and sea monsters. Now, astronomers using the Fermi Gamma-ray Space Telescope find themselves in the same situation as cartographers of old. A new study of the ever-present fog of gamma rays from sources outside our galaxy shows that less than a third of the emission arises from what astronomers once considered the most likely suspects—black-hole-powered jets from active galaxies. "Active galaxies can explain less than 30 percent of the extragalactic gamma-ray background Fermi sees," said Marco Ajello, an astrophysicist at the Kavli Institute for Particle Astrophysics and Cosmology, jointly located at SLAC National Accelerator Laboratory and Stanford University. "That leaves a lot of room for scientific discovery as we puzzle out what else may be responsible." Ajello presented his findings Tuesday at a meeting of the American Astronomical Society's High-Energy Astrophysics Division in Waikoloa, Hawaii. The sky glows in gamma rays even far away from bright sources, such as pulsars and gas clouds within our own Milky Way galaxy or the most luminous active galaxies. According to the conventional explanation, this background glow represents the accumulated emission of a vast number of active galaxies that are simply too faint and too distant to be resolved as discrete gamma-ray sources. "Thanks to Fermi, we now know for certain that this is not the case," Ajello said. A paper on the findings has been submitted to The Astrophysical Journal.. Happy Anniversary, Fermi TelescopeOn February 28, 2000, NASA announced the award to Stanford University for development of a space-based gamma ray telescope named GLAST. The telescope was to be a collaboration of NASA, the Department of Energy, and five non-US nations. The management of the project was to be centered at SLAC. GLAST is now the Fermi Gamma-ray Space Telescope. Noontime Concert Tomorrow:
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