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Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Experimentelle Elementarteilchenphysik

The H Collaboration (2008)

HESS upper limits for Kepler's supernova remnant

aap, 488:219-223.

Aims: Observations of Kepler's supernova remnant (G4.5+6.8) with the HESS telescope array in 2004 and 2005 with a total live time of 13 h are presented. Methods: Stereoscopic imaging of Cherenkov radiation from extensive air showers is used to reconstruct the energy and direction of the incident gamma rays. Results: No evidence for a very high energy (VHE: >100 GeV) gamma-ray signal from the direction of the remnant is found. An upper limit (99% confidence level) on the energy flux in the range 230 GeV-12.8 TeV of 8.6 × 10^-13 erg cm^-2 s^-1 is obtained. Conclusions: In the context of an existing theoretical model for the remnant, the lack of a detectable gamma-ray flux implies a distance of at least 6.4 kpc. A corresponding upper limit for the density of the ambient matter of 0.7 cm^-3 is derived. With this distance limit, and assuming a spectral index Gamma = 2, the total energy in accelerated protons is limited to E^p < 8.6 × 10^49 erg. In the synchrotron/inverse Compton framework, extrapolating the power law measured by RXTE between 10 and 20 keV down in energy, the predicted gamma-ray flux from inverse Compton scattering is below the measured upper limit for magnetic field values greater than 52 mu G.

Provided by the SAO/NASA Astrophysics Data System