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Title:	Observations of the Crab Pulsar between 25 and 100 GeV with the MAGIC I Telescope
Author:	Cañellas, A.; Marcote Martin, Benito; Munar i Adrover, Pere; Moldón Vara, Francisco Javier; Paredes i Poy, Josep Maria; Ribó Gomis, Marc; Zabalza de Torres, Víctor
Other authors:	Universitat de Barcelona
Abstract:	We report on the observation of $\gamma$-rays above 25\,GeV from the Crab pulsar (PSR B0532+21) using the MAGIC I telescope. Two data sets from observations during the winter period 2007/2008 and 2008/2009 are used. In order to discuss the spectral shape from 100\,MeV to 100\,GeV, one year of public {\it Fermi} Large Area Telescope ({\it Fermi}-LAT) data are also analyzed to complement the MAGIC data. The extrapolation of the exponential cutoff spectrum determined with the Fermi-LAT data is inconsistent with MAGIC measurements, which requires a modification of the standard pulsar emission models. In the energy region between 25 and 100\,GeV, the emission in the P1 phase (from -0.06 to 0.04, location of the main pulse) and the P2 phase (from 0.32 to 0.43, location of the interpulse) can be described by power laws with spectral indices of $-3.1 \pm 1.0_{stat} \pm 0.3_{syst}$ and $-3.5 \pm 0.5_{stat} \pm 0.3_{syst}$, respectively. Assuming an asymmetric Lorentzian for the pulse shape, the peak positions of the main pulse and the interpulse are estimated to be at phases $-0.009 \pm 0.007$ and $0.393 \pm 0.009$, while the full widths at half maximum are $0.025 \pm 0.008$ and $0.053 \pm 0.015$, respectively.
Subject(s):	-Estels -Raigs gamma -Stars -Gamma rays
Rights:	(c) American Astronomical Society, 2011
Document type:	Article Article - Published version
Published by:	Institute of Physics (IOP)
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