Institute: MPI für Kernphysik     Collection: High-Energy Astrophysics     Display Documents

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ID: 197913.0, MPI für Kernphysik / High-Energy Astrophysics
The Crab Nebula and Pulsar between 500 GeV and 80 TeV: Observations with the HEGRA stereoscopic air Cherenkov telescopes
Authors:
Language:English
Date of Publication (YYYY-MM-DD):2004-10-20
Title of Journal:Astrophysical Journal
Volume:614
Issue / Number:2 Part 1
Start Page:897
End Page:913
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:The Crab supernova remnant has been observed regularly with the stereoscopic system of 5 imaging air Cherenkov telescopes that was part of the High Energy Gamma Ray Astronomy (HEGRA) experiment. In total, close to 400 hours of useful data have been collected from 1997 until 2002. The spectrum extends up to energies of 80 TeV and is well matched by model calculations in the framework of inverse Compton scattering of various seed photons in the nebula including for the first time a recently detected compact emission region at mm-wavelengths. The observed indications for a gradual steepening of the energy spectrum in data is expected in the inverse Compton emission model.The average magnetic field in the emitting volume is determined to be $(161.6\pm0.8mathrm{stat}\pm18_\mathrm{sys}) \mu$G. The presence of protons in the nebula is not required to explain the observed flux and upper limits on the injected power of protons are calculated being as low as 20 % of the total spin down luminosity for bulk Lorentz factors of the wind in the range of $10^4-10^6$.The position and size of the emission region have been studied over a wide range of energies. The position is shifted by 13\arcsec to the west of the pulsar with a systematic uncertainty of 25\arcsec. No significant shift in the position with energy is observed. The size of the emission region is constrained to be less than 2\arcmin at energies between 1 and 10 TeV. Above 30 TeV the size is constrained to be less than 3\arcmin.No indications for pulsed emission has been found and upper limits in differential bins of energy have been calculated reaching typically 1-3 % of the unpulsed component.
External Publication Status:published
Document Type:Article
Affiliations:
External Affiliations:Max Planck Inst Phys & Astrophys, D-80805 Munich, Germany; Univ Complutense, Fac Ciencias Fis, E-28040 Madrid, Spain; Univ Hamburg, Inst Phys Expt, D-22761 Hamburg, Germany; Univ Kiel, Inst Expt & Angew Phys, D-24118 Kiel, Germany; Univ Wuppertal, Fachbereich Phys, D-42097 Wuppertal, Germany; Yerevan Phys Inst, Yerevan 375036, Armenia
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