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Originally published in Science Express on 16 October 2008
Science 21 November 2008:
Vol. 322. no. 5905, pp. 1221 - 1224
DOI: 10.1126/science.1164718
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Reports

Observation of Pulsed {gamma}-Rays Above 25 GeV from the Crab Pulsar with MAGIC

The MAGIC Collaboration*

One fundamental question about pulsars concerns the mechanism of their pulsed electromagnetic emission. Measuring the high-end region of a pulsar's spectrum would shed light on this question. By developing a new electronic trigger, we lowered the threshold of the Major Atmospheric {gamma}-ray Imaging Cherenkov (MAGIC) telescope to 25 giga–electron volts. In this configuration, we detected pulsed {gamma}-rays from the Crab pulsar that were greater than 25 giga–electron volts, revealing a relatively high cutoff energy in the phase-averaged spectrum. This indicates that the emission occurs far out in the magnetosphere, hence excluding the polar-cap scenario as a possible explanation of our measurement. The high cutoff energy also challenges the slot-gap scenario.

* The full list of authors and affiliations is presented at the end of this paper.

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