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

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.

Astronomy & Astrophysics 550, A4 (2013)
ArXiv pre-print

Auxiliary informations

Spectral energy distribution of the EBL measured with HESS

1 sigma confidence contour including statistical and systematic uncertainties

Wavelength LambdaF_Lambda_min LambdaF_Lambda_max
[µm] [nW m-2 sr-1]
0.302 2.4 3.83
0.304 2.42 3.86
0.307 2.45 3.9
0.309 2.47 3.94
0.312 2.5 3.98
0.315 2.52 4.02
0.317 2.55 4.07
0.32 2.58 4.11
0.322 2.61 4.15
0.325 2.63 4.2
0.328 2.66 4.24
0.331 2.69 4.29
0.333 2.72 4.34
0.336 2.75 4.39
0.339 2.78 4.44
0.342 2.82 4.49
0.345 2.85 4.54
0.347 2.88 4.59
0.35 2.92 4.65
0.353 2.95 4.7
0.356 2.99 4.76
0.359 3.02 4.82
0.362 3.06 4.88
0.365 3.1 4.94
0.368 3.14 5
0.371 3.18 5.06
0.374 3.22 5.13
0.377 3.26 5.19
0.381 3.3 5.26
0.384 3.34 5.33
0.387 3.39 5.4
0.39 3.43 5.47
0.393 3.48 5.54
0.397 3.52 5.62
0.4 3.58 5.7
0.403 3.65 5.81
0.407 3.71 5.92
0.41 3.78 6.03
0.413 3.86 6.14
0.417 3.93 6.26
0.42 4 6.37
0.424 4.07 6.49
0.427 4.14 6.6
0.431 4.22 6.72
0.435 4.29 6.84
0.438 4.36 6.95
0.442 4.44 7.07
0.445 4.51 7.19
0.449 4.59 7.31
0.453 4.66 7.43
0.457 4.74 7.56
0.46 4.82 7.68
0.464 4.89 7.8
0.468 4.97 7.92
0.472 5.05 8.05
0.476 5.13 8.17
0.48 5.21 8.3
0.484 5.28 8.42
0.488 5.36 8.55
0.492 5.44 8.67
0.496 5.52 8.8
0.5 5.6 8.92
0.504 5.68 9.05
0.509 5.76 9.18
0.513 5.84 9.3
0.517 5.92 9.43
0.521 5.99 9.55
0.526 6.07 9.68
0.53 6.15 9.81
0.534 6.23 9.93
0.539 6.31 10.1
0.543 6.39 10.2
0.548 6.47 10.3
0.552 6.52 10.4
0.557 6.58 10.5
0.562 6.63 10.6
0.566 6.68 10.7
0.571 6.74 10.7
0.576 6.79 10.8
0.581 6.85 10.9
0.585 6.91 11
0.59 6.96 11.1
0.595 7.02 11.2
0.6 7.07 11.3
0.605 7.13 11.4
0.61 7.19 11.5
0.615 7.25 11.6
0.62 7.31 11.6
0.626 7.36 11.7
0.631 7.42 11.8
0.636 7.48 11.9
0.641 7.54 12
0.647 7.6 12.1
0.652 7.66 12.2
0.657 7.72 12.3
0.663 7.79 12.4
0.668 7.85 12.5
0.674 7.91 12.6
0.68 7.97 12.7
0.685 8.03 12.8
0.691 8.1 12.9
0.697 8.16 13
0.702 8.23 13.1
0.708 8.29 13.2
0.714 8.36 13.3
0.72 8.42 13.4
0.726 8.49 13.5
0.732 8.55 13.6
0.738 8.62 13.7
0.744 8.69 13.8
0.751 8.76 14
0.757 8.82 14.1
0.763 8.89 14.2
0.769 8.96 14.3
0.776 9.03 14.4
0.782 9.1 14.5
0.789 9.17 14.6
0.795 9.24 14.7
0.802 9.32 14.9
0.809 9.42 15
0.815 9.51 15.2
0.822 9.59 15.3
0.829 9.68 15.4
0.836 9.77 15.6
0.843 9.86 15.7
0.85 9.94 15.8
0.857 10 16
0.864 10.1 16.1
0.871 10.2 16.2
0.879 10.3 16.4
0.886 10.4 16.5
0.893 10.4 16.6
0.901 10.5 16.8
0.908 10.6 16.9
0.916 10.7 17
0.923 10.7 17.1
0.931 10.8 17.2
0.939 10.9 17.3
0.946 10.9 17.4
0.954 11 17.6
0.962 11.1 17.7
0.97 11.1 17.8
0.978 11.2 17.9
0.987 11.3 18
0.995 11.3 18.1
1 11.4 18.1
1.01 11.4 18.2
1.02 11.5 18.3
1.03 11.5 18.3
1.04 11.5 18.4
1.05 11.6 18.5
1.05 11.6 18.5
1.06 11.7 18.6
1.07 11.7 18.7
1.08 11.7 18.7
1.09 11.8 18.8
1.1 11.8 18.8
1.11 11.8 18.9
1.12 11.9 18.9
1.13 11.9 19
1.14 11.9 19
1.15 12 19.1
1.15 12 19.1
1.16 12 19.1
1.17 12 19.2
1.18 12.1 19.2
1.19 12.1 19.2
1.2 11.4 18.4
1.21 11.4 18.4
1.22 11.4 18.4
1.23 11.5 18.5
1.24 11.5 18.5
1.25 11.5 18.5
1.26 11.5 18.5
1.28 11.5 18.6
1.29 11.5 18.6
1.3 11.5 18.6
1.31 11.5 18.6
1.32 11.5 18.6
1.33 11.5 18.6
1.34 11.5 18.6
1.35 11.5 18.6
1.36 11.5 18.6
1.37 11.5 18.6
1.39 11.5 18.6
1.4 11.5 18.6
1.41 11.5 18.6
1.42 11.5 18.6
1.43 11.5 18.6
1.44 11.5 18.6
1.46 11.5 18.6
1.47 11.5 18.6
1.48 11.5 18.5
1.49 11.5 18.5
1.51 11.5 18.5
1.52 11.5 18.5
1.53 11.4 18.4
1.54 11.4 18.4
1.56 11.4 18.4
1.57 11.4 18.4
1.58 11.4 18.3
1.59 11.3 18.3
1.61 11.3 18.3
1.62 11.3 18.2
1.64 11.3 18.2
1.65 11.2 18.1
1.66 11.2 18.1
1.68 11.2 18
1.69 11.2 18
1.7 11.1 17.9
1.72 11.1 17.9
1.73 11 17.8
1.75 11 17.7
1.76 11 17.7
1.78 10.9 17.6
1.79 10.9 17.5
1.81 10.8 17.5
1.82 10.8 17.4
1.84 10.7 17.3
1.85 10.7 17.2
1.87 10.6 17.2
1.88 10.6 17.1
1.9 10.5 17
1.91 10.5 16.9
1.93 10.4 16.9
1.95 10.4 16.8
1.96 10.3 16.7
1.98 10.3 16.6
1.99 10.2 16.5
2.01 10.2 16.4
2.03 10.1 16.3
2.04 10.1 16.3
2.06 10 16.2
2.08 9.97 16.1
2.1 9.91 16
2.11 9.86 15.9
2.13 9.8 15.8
2.15 9.74 15.7
2.17 9.68 15.6
2.18 9.62 15.5
2.2 9.56 15.4
2.22 9.5 15.3
2.24 9.44 15.2
2.26 9.38 15.1
2.28 9.32 15
2.3 9.26 14.9
2.32 9.2 14.8
2.33 9.13 14.7
2.35 9.07 14.6
2.37 9.01 14.5
2.39 8.94 14.4
2.41 8.88 14.3
2.43 8.82 14.2
2.45 8.75 14.1
2.47 8.69 14
2.49 8.62 13.9
2.52 8.55 13.8
2.54 8.49 13.7
2.56 8.42 13.6
2.58 8.36 13.5
2.6 8.29 13.4
2.62 8.22 13.3
2.64 8.16 13.2
2.67 8.09 13
2.69 8.02 12.9
2.71 7.95 12.8
2.73 7.89 12.7
2.76 7.82 12.6
2.78 7.75 12.5
2.8 7.68 12.4
2.82 7.62 12.3
2.85 7.55 12.2
2.87 7.48 12.1
2.9 7.41 12
2.92 7.34 11.8
2.94 7.27 11.7
2.97 7.21 11.6
2.99 7.14 11.5
3.02 7.07 11.4
3.04 7 11.3
3.07 6.93 11.2
3.09 6.86 11.1
3.12 6.79 11
3.15 6.72 10.8
3.17 6.66 10.7
3.2 6.59 10.6
3.22 6.52 10.5
3.25 6.45 10.4
3.28 6.38 10.3
3.31 6.32 10.2
3.33 6.25 10.1
3.36 6.18 9.97
3.39 6.12 9.87
3.42 6.05 9.76
3.45 5.98 9.65
3.47 5.92 9.55
3.5 5.85 9.44
3.53 5.79 9.33
3.56 5.72 9.23
3.59 5.66 9.13
3.62 5.59 9.02
3.65 5.53 8.92
3.68 5.46 8.81
3.71 5.39 8.69
3.74 5.32 8.57
3.77 5.25 8.46
3.81 5.18 8.35
3.84 5.11 8.24
3.87 5.04 8.13
3.9 4.98 8.03
3.93 4.91 7.93
3.97 4.85 7.82
4 4.79 7.73
4.03 4.73 7.63
4.07 4.67 7.53
4.1 4.61 7.44
4.13 4.55 7.35
4.17 4.5 7.26
4.2 4.44 7.17
4.24 4.39 7.08
4.27 4.34 6.99
4.31 4.28 6.91
4.34 4.23 6.83
4.38 4.18 6.75
4.42 4.13 6.67
4.45 4.09 6.59
4.49 4.04 6.51
4.53 3.99 6.43
4.57 3.94 6.35
4.6 3.89 6.27
4.64 3.84 6.19
4.68 3.79 6.11
4.72 3.75 6.04
4.76 3.7 5.97
4.8 3.66 5.9
4.84 3.61 5.83
4.88 3.57 5.76
4.92 3.53 5.7
4.96 3.49 5.64
5 3.46 5.57
5.04 3.42 5.51
5.09 3.38 5.46
5.13 3.35 5.4
5.17 3.31 5.34
5.21 3.28 5.29
5.26 3.25 5.24
5.3 3.22 5.19
5.34 3.19 5.14
5.39 3.16 5.09
5.43 3.13 5.04
5.48 3.1 5
5.52 2.12 4.57
5.57 2.1 4.53
5.62 2.08 4.49
5.66 2.06 4.45
5.71 2.05 4.42
5.76 2.03 4.38
5.81 2.02 4.35
5.85 2.01 4.33
5.9 2 4.31
5.95 1.99 4.29
6 1.98 4.27
6.05 1.97 4.25
6.1 1.96 4.22
6.15 1.94 4.2
6.2 1.93 4.17
6.26 1.92 4.14
6.31 1.91 4.12
6.36 1.89 4.09
6.41 1.88 4.06
6.47 1.87 4.03
6.52 1.85 4
6.57 1.84 3.96
6.63 1.82 3.93
6.68 1.8 3.9
6.74 1.78 3.84
6.8 1.75 3.78
6.85 1.72 3.72
6.91 1.7 3.67
6.97 1.68 3.62
7.02 1.65 3.57
7.08 1.63 3.52
7.14 1.61 3.48
7.2 1.59 3.44
7.26 1.57 3.4
7.32 1.56 3.36
7.38 1.54 3.32
7.44 1.52 3.28
7.51 1.51 3.25
7.57 1.49 3.22
7.63 1.48 3.19
7.69 1.46 3.16
7.76 1.45 3.13
7.82 1.44 3.1
7.89 1.43 3.08
7.95 1.42 3.06
8.02 1.41 3.04
8.09 1.4 3.02
8.15 1.39 3
8.22 1.38 2.98
8.29 1.38 2.97
8.36 1.37 2.95
8.43 1.36 2.94
8.5 1.36 2.93
8.57 1.35 2.91
8.64 1.35 2.9
8.71 1.34 2.89
8.78 1.34 2.88
8.86 1.33 2.87
8.93 1.33 2.87
9.01 1.32 2.86
9.08 1.32 2.85
9.16 1.32 2.85
9.23 1.32 2.84
9.31 1.32 2.84
9.39 1.31 2.84
9.46 1.31 2.83
9.54 1.31 2.83
9.62 1.31 2.83
9.7 1.31 2.83
9.78 1.31 2.83
9.87 1.31 2.83
9.95 1.31 2.84
10 1.32 2.84
10.1 1.32 2.84
10.2 1.32 2.85
10.3 1.32 2.85
10.4 1.33 2.86
10.5 1.33 2.87
10.5 1.33 2.88
10.6 1.34 2.88
10.7 1.34 2.89
10.8 1.35 2.9
10.9 1.35 2.92
11 1.36 2.93
11.1 1.36 2.94
11.2 1.37 2.95
11.3 1.38 2.97
11.4 1.38 2.98
11.5 1.39 3
11.5 1.4 3.02
11.6 1.41 3.04
11.7 1.42 3.06
11.8 1.43 3.08
11.9 1.43 3.1
12 1.45 3.13
12.1 1.47 3.18
12.2 1.49 3.22
12.3 1.51 3.27
12.4 1.53 3.31
12.5 1.55 3.35
12.6 1.57 3.4
12.8 1.59 3.44
12.9 1.61 3.48
13 1.63 3.52
13.1 1.65 3.56
13.2 1.67 3.61
13.3 1.69 3.65
13.4 1.71 3.69
13.5 1.73 3.73
13.6 1.74 3.76
13.7 1.76 3.8
13.9 1.78 3.84
14 1.8 3.88
14.1 1.81 3.91
14.2 1.83 3.95
14.3 1.84 3.98
14.4 1.86 4.02
14.6 1.88 4.05
14.7 1.89 4.08
14.8 1.91 4.11
14.9 1.92 4.14
15.1 1.93 4.17
15.2 1.94 4.18
15.3 1.95 4.2
15.4 1.95 4.22
15.6 1.96 4.23
15.7 1.97 4.25
15.8 1.98 4.26
15.9 1.98 4.28
16.1 1.99 4.29
16.2 2 4.31
16.4 2 4.32
16.5 2.01 4.34

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