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Astronomy and Astrophysics 448 (2006) L43-L47
First detection of a VHE gamma-ray spectral maximum from a Cosmic source: H.E.S.S. discovery of the Vela X nebula
F. Aharonian, A.G. Akhperjanian, A.R. Bazer-Bachi, M. Beilicke, Wystan Benbow, David Berge, K. Bernlohr, C. Boisson, O. Bolz, V. Borrel, I. Braun, F. Breitling, A.M. Brown, R. Buhler, S. Carrigan, P.M. Chadwick, L.-M. Chounet1, R. Cornils, L. Costamante, B. Degrange1, H.J. Dickinson, A. Djannati-Atai2, L.O'C. Drury, G. Dubus1, K. Egberts, D. Emmanoulopoulos, P. Espigat2, F. Feinstein3, G. Fontaine1, S. Funk, Y. Gallant3, B. Giebels1, J.F. Glicenstein, P. Goret, C. Hadjichristidis, D. Hauser, M. Hauser, G. Heinzelmann, G. Henri, G. Hermann, J.A. Hinton, W. Hofmann, M. Holleran, Dieter Horns, A. Jacholkowska3, O.C. de Jager, B. Khelifi1, S. Klages, Nu. Komin, A. Konopelko, I.J. Latham, R. Le Gallou, A. Lemiere2, M. Lemoine-Goumard1, T. Lohse, J.M. Martin, O. Martineau-Huynh3, A. Marcowith, C. Masterson, T.J.L. Mccomb, M. De Naurois3, D. Nedbal, S.J. Nolan, A. Noutsos, K.J. Orford, J.L. Osborne, M. Ouchrif3, M. Panter, G. Pelletier4, S. Pita2, G. Puhlhofer, M. Punch2, B.C. Raubenheimer, M. Raue, S.M. Rayner, A. Reimer, O. Reimer, J. Ripken, L. Rob, L. Rolland, G. Rowell, V. Sahakian, L. Sauge4, S. Schlenker, R. Schlickeiser, C. Schuster, U. Schwanke, M. Siewert, H. Sol, D. Spangler, R. Steenkamp, C. Stegmann, G. Superina, J.-P. Tavernet3, R. Terrier2, C.G. Theoret2, M. Tluczykont1, C. Van Eldik, G. Vasileiadis3, C. Venter, P. Vincent3, H.J. Volk, S.J. Wagner, M. Ward
HESS Collaboration(s)

The Vela supernova remnant (SNR) is a complex region containing a number of sources of non-thermal radiation. The inner section of this SNR, within 2 degrees of the pulsar PSR B0833-45, has been observed by the H.E.S.S. gamma-ray atmospheric Cherenkov detector in 2004 and 2005. A strong signal is seen from an extended region to the south of the pulsar, within an integration region of radius 0.8 deg. around the position (RA = 08h 35m 00s, dec = -45 deg. 36' J2000.0). The excess coincides with a region of hard X-ray emission seen by the ROSAT and ASCA satellites. The observed energy spectrum of the source between 550 GeV and 65 TeV is well fit by a power law function with photon index = 1.45 +/- 0.09(stat) +/- 0.2(sys) and an exponential cutoff at an energy of 13.8 +/- 2.3(stat) +/- 4.1(sys) TeV. The integral flux above 1 TeV is (1.28 +/- 0.17 (stat) +/- 0.38(sys)) x 10^{-11} cm^{-2} s^{-1}. This result is the first clear measurement of a peak in the spectral energy distribution from a VHE gamma-ray source, likely related to inverse Compton emission. A fit of an Inverse Compton model to the H.E.S.S. spectral energy distribution gives a total energy in non-thermal electrons of ~2 x 10^{45} erg between 5 TeV and 100 TeV, assuming a distance of 290 parsec to the pulsar. The best fit electron power law index is 2.0, with a spectral break at 67 TeV.
1 :  LLR - Laboratoire Leprince-Ringuet
2 :  APC - UMR 7164 - AstroParticule et Cosmologie
3 :  LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
4 :  LPTA - Laboratoire de Physique Théorique et Astroparticules
Physique/Astrophysique/Cosmologie et astrophysique extra-galactique

Planète et Univers/Astrophysique
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