VHE γ-ray observation of the Crab Nebula and its pulsar with the MAGIC Telescope

Abstract

We report about very high energy (VHE) γ-ray observations of the Crab Nebula with the MAGIC telescope. The γ-ray flux from the nebula was measured between 60 GeV and 9 TeV. The energy spectrum can be described by a curved power law dF/dE = f0(E/300 GeV)[a+blog10(E/300 GeV)] with a flux normalization f0 of (6.0 ± 0.2stat) × 10−10 cm−2 s−1 TeV−1, a = − 2.31 ± 0.06stat, and b = − 0.26 ± 0.07stat. The peak in the spectral energy distribution is estimated at 77 ± 35 GeV. Within the observation time and the experimental resolution of the telescope, the γ-ray emission is steady and pointlike. The emission's center of gravity coincides with the position of the pulsar. Pulsed γ-ray emission from the pulsar could not be detected. We constrain the cutoff energy of the pulsed spectrum to be less than 27 GeV, assuming that the differential energy spectrum has an exponential cutoff. For a superexponential shape, the cutoff energy can be as high as 60 GeV.