HEAPOW: More from the Crab (2011 Oct 17)
Just when it was thought the Crab couldn't get any stranger, it has. The Crab, to remind you, is the remnant of a star which was observed to explode as a supernova in A. D. 1054 and which consists of an ornate, bright nebula surrounding a neutron star which spins 30 times per second. Radiation from the neutron star's magnetic poles produces a flash of light each time the star spins around. The Crab Pulsar is known to produce flashes of radio radiation, optical light and X-rays. Now, a set of ground-based gamma-ray telescopes called VERITAS has shown that the Crab's pulsations extend at least up to Gamma-ray energies. VERITAS, the Very Energetic Radiation Imaging Telescope Array System, consists of four 12-meter optical reflectors which work by detecting Cherenkov radiation produced as a high energy gamma-ray or superfast particle hits the earth's upper atmosphere. The figure above shows the pulsed Gamma-ray emission from the Crab detected by VERITAS. This is first time very-high-energy gamma rays have ever been detected from a pulsar and indicates that the emission originates at a distance of more than 10 times the neutron star's radius (which is only about 10 kilometers, roughly the size of the Washington DC beltway). This high-energy pulsation detected by VERITAS cannot be explained on the basis of present pulsar models.
VERITAS: Detection of Pulsed Gamma Rays Above 100 GeV from the Crab Pulsar
http://asterisk.apod.com/viewtopic.php? ... 92#p159592
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