The intensity of the extragalactic background (EBL), the accumulated optical and infrared emissions since the first stars, is the subject of a decades-long tension in the optical band. These photons form a target field that attenuates the γ-ray flux from extragalactic sources. This Letter reports the first γ-ray measurement of the EBL spectrum at z = 0 that is purely parametric and independent of EBL evolution with redshift over a wavelength range from 0.18 to 120 μm. Our method extracts the EBL absorption imprint on more than 260 archival TeV spectra from the STeVECat catalog by marginalizing nuisance parameters describing the intrinsic emission and instrumental uncertainties. We report an intensity at 600 nm of 6.9 ± 1.9 nW m⁻² sr⁻¹ × h ₇₀, which is indistinguishable from the intensity derived from integrated galaxy light (IGL) and compatible with direct measurements taken beyond Pluto’s orbit. We exclude with 95% confidence diffuse contributions to the EBL with an intensity relative to the IGL, f _diff, greater than 20% and provide a measurement of the expansion rate of the Universe at z = 0, H0=67−6+7 km s⁻¹ Mpc ⁻¹ × (1 + f _diff), which is EBL-model independent. IGL, direct, and γ-ray measurements agree on the EBL intensity in the optical band, finally reaching a cosmological optical convergence.

中文翻译：

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宇宙学光学会聚：来自 TeV 伽马射线的星系外背景光


星系外背景 （EBL） 的强度，即自第一颗恒星以来累积的光学和红外发射，是光学波段长达数十年的紧张主题。这些光子形成一个目标场，衰减来自银河系外源的γ射线通量。本信报告了 z = 0 处 EBL 光谱的首次γ射线测量，该测量是纯参数性的，独立于 EBL 演变，在 0.18 至 120 μm 的波长范围内发生红移。我们的方法通过边缘化描述内禀发射和仪器不确定性的干扰参数，从 STeVECat 目录中提取了 260 多个存档 TeV 光谱上的 EBL 吸收印记。我们报告了 600 nm 处的强度为 6.9 ± 1.9 nW ^{m-2 sr-1} × h₇₀，这与来自集成星系光 （IGL） 的强度没有区别，并且与在冥王星轨道之外进行的直接测量兼容。我们以 95% 的置信度排除了强度相对于 IGL 的弥散贡献，f_diff 大于 20%，并提供了宇宙在 z = 0、H0=67−6+7 km s⁻¹ Mpc ⁻¹ × （1 + f_diff） 时的膨胀率的测量，这与 EBL 模型无关。IGL、直接和γ射线测量与光学波段中的 EBL 强度一致，最终达到宇宙学光学会聚。