62 articles – 637 Notices  [english version]
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Nature 440 (2006) 1018-1021
A low level of extragalactic background light with gamma-ray spectra from distant blazars
F. Aharonian, A. G. Akhperjanian, A. R. Bazer-Bachi, M. Beilicke, W. Benbow, D. Berge, K. Bernlöhr, C. Boisson, O. Bolz, V. Borrel, I. Braun, F. Breitling, A. M. Brown, P. M. Chadwick, L.-M. Chounet1, R. Cornils, L. Costamante, B. Degrange1, H.J. Dickinson, A. Djannati-Ataï2, Drury L. O'C., G. Dubus1, D. Emmanoulopoulos, P. Espigat2, F. Feinstein3, G. Fontaine1, Y. Fuchs, S. Funk, Y. A. Gallant3, B. Giebels1, S. Gillessen, J.F. Glicenstein, P. Goret, C. Hadjichristidis, M. Hauser, G. Heinzelmann, G. Henri, G. Hermann, J. A. Hinton, W. Hofmann, M. Holleran, D. Horns, A. Jacholkowska3, O.C. Dejager, B. Khélifi, Nu. Komin, A. Konopelko, I. J. Latham, R. Le Gallou, A. Lemière2, M. Lemoine-Goumard1, N. Leroy1, T. Lohse, J.M. Martin, O. Martineau-Huynh4, A. Marcowith, C. Masterson, T. J. L. Mccomb, M. De Naurois4, S. J. Nolan, A. Noutsos, K. J. Orford, J. L. Osborne, M. Ouchrif4, M. Panter, G. Pelletier, S. Pita2, G. Pühlhofer, M. Punch2, B. C. Raubenheimer, M. Raue, J. Raux4, S. M. Rayner, A. Reimer, O. Reimer, J. Ripken, L. Rob, L. Rolland4, G. Rowell, V. Sahakian, L. Saugé, S. Schlenker, R. Schlickeiser, C. Schuster, U. Schwanke, M. Siewert, H. Sol, D. Spangler, R. Steenkamp, C. Stegmann, J.-P. Tavernet4, R. Terrier2, C.G. Théoret2, M. Tluczykont1, G. Vasileiadis3, C. Venter, P. Vincent4, H. J. Völk, S. J. Wagner
HESS Collaboration(s)

The diffuse Extragalactic Background Light (EBL) contains unique information about the epochs of formation and the history of evolution of galaxies. Unfortunately, direct measurements are subject to large systematic uncertainties due to the difficulties in the accurate model-based subtraction of the bright foregrounds. An alternative approach is based on the detection and identification of EBL absorption features in high-energy spectra of objects of known redshift. Here we exploit this method on the blazars H 2356-309 (z=0.165) and 1ES 1101-232 (z=0.186), newly discovered at TeV energies by the H.E.S.S. Collaboration. They are the most distant sources with measured spectra known so far at these energies. Their hard spectra provide the most stringent upper limit to date on the EBL in the Opt--NIR band, which appears significantly lower than expected from the current "direct" estimates and very close to the absolute lower limit represented by the integrated light of resolved galaxies. In addition to important cosmological implications, this result shows that the intergalactic space is more transparent to gamma-rays than previously thought, expanding the horizon of the TeV Universe.
1 :  LLR - Laboratoire Leprince-Ringuet
2 :  APC - UMR 7164 - AstroParticule et Cosmologie
3 :  LPTA - Laboratoire de Physique Théorique et Astroparticules
4 :  LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
Physique/Astrophysique/Cosmologie et astrophysique extra-galactique

Planète et Univers/Astrophysique
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