Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S.

Type Journal Article
Names H.E.S.S. Collaboration, A. Abramowski, F. Acero, F. Aharonian, A. G. Akhperjanian, G. Anton, S. Balenderan, A. Balzer, A. Barnacka, Y. Becherini, J. Becker Tjus, K. Bernlöhr, E. Birsin, J. Biteau, A. Bochow, C. Boisson, J. Bolmont, P. Bordas, J. Bruc
Publication Astronomy and Astrophysics
Volume 550
Pages 4
Journal Abbreviation Astronomy and Astrophysics
Date February 1, 2013
DOI 10.1051/0004-6361/201220355;
ISSN 0004-6361
Library Catalog NASA ADS
Abstract The extragalactic background light (EBL) is the diffuse radiation with the second highest energy density in the Universe after the cosmic microwave background. The aim of this study is the measurement of the imprint of the EBL opacity to γ-rays on the spectra of the brightest extragalactic sources detected with the High Energy Stereoscopic System (H.E.S.S.). The originality of the method lies in the joint fit of the EBL optical depth and of the intrinsic spectra of the sources, assuming intrinsic smoothness. Analysis of a total of ~105γ-ray events enables the detection of an EBL signature at the 8.8σ level and constitutes the first measurement of the EBL optical depth using very-high energy (E > 100 GeV) γ-rays. The EBL flux density is constrained over almost two decades of wavelengths [0.30 μm, 17 μm] and the peak value at 1.4 μm is derived as λFλ = 15 ± 2stat ± 3sys nW m-2 sr-1. Appendix A is available in electronic form at
Tags BL Lacertae objects: general, cosmic background radiation, gamma rays: galaxies
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