Author(s): Aharonian F., Bazer-Bachi A.R., Boisson C., Borrel V., Brion E., Boutelier T., Chounet L.-M., Coignet G., Degrange B., Djannati-Ataï A., Dubois F., Dubus G., Espigat P., Farnier C., Feinstein F., Fiasson A., Fontaine G., Gallant Y., Giebels B., Glicenstein J.F., Goret P., Henri G., Jacholkowska Agnieszka, Khélifi B., Komin Nukri, Lamanna G., Lemoine-Goumard M., Marcowith A., Renaud M., Vasileiadis G.
(Article) Published:
Annual Review Of Astronomy And Astrophysics, vol. 488 p.219-223 (2008)
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Ref HAL: in2p3-00289653_v1
Ref Arxiv: 0806.3347
DOI: 10.1051/0004-6361:200809401
Ref. & Cit.: NASA ADS
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22 citations
Abstract:
Observations of Kepler's supernova remnant (G4.5+6.8) with the H.E.S.S. telescope array in 2004 and 2005 with a total live time of 13 h are presented. Stereoscopic imaging of Cherenkov radiation from extensive air showers is used to reconstruct the energy and direction of the incident gamma rays. 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 x 10^{-13} erg cm^{-2} s^{-1} is obtained. 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 x 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 muG.
Comments: 5 pages, 3 figures; Accepted for publication in A&A on June 12, 2008