A GeV-TeV Measurement of the Extragalactic Background Light

Abstract

The Extragalactic Background Light (EBL) can be probed via the absorption imprint it leaves in the spectra of gamma-ray sources ($\gamma \gamma \to e^{-}{e}^{+}$). We recently developed a dedicated technique to reconstruct the EBL, and its evolution with redshift, from $\gamma$ ray optical depth data using a large sample of blazars detected by the $Fermi$ Large Area Telescope. Here, we extend this dataset to the TeV regime using ground-based Cherenkov observations of 38 blazars and report the first homogeneous measurement of the EBL spectral intensity covering the ultraviolet to infrared wavelengths ($\sim$0.1-100$\mu \mathrm{m}$). A minimal EBL throughout the wavelength range with respect to integrated galaxy light is found, allowing little additional unresolved emission from faint or truly diffuse populations setting an upper limit of $\lesssim 4\mathrm{nW}\cdot {\mathrm{m}}^{-2}\mathrm{s}{\mathrm{r}}^{-1}$ at 1.4 $\mu \mathrm{m}$. In particular, the cosmic optical background (COB) at $z=0$ is found to be $27.8_{-2.0}^{+2.1}\mathrm{nW}\cdot {\mathrm{m}}^{-2}\mathrm{s}{\mathrm{r}}^{-1}$. This work lays the foundation for accurate gamma-ray measurements of the EBL across its whole spectral range using a combination of GeV and TeV data.

References in corpus (7)

• The Imprint of The Extragalactic Background Light in the Gamma-Ray Spectra of Blazars
• New limits on the density of the extragalactic background light in the optical to the far-infrared from the spectra of all known TeV blazars
• Measurement of the EBL spectral energy distribution using the VHE gamma-ray spectra of H.E.S.S. blazars
• The Resolved Near-Infrared Extragalactic Background
• The Resolved NIR Extragalactic Background
• Extragalactic background Light: a measurement at 400 nm using dark cloud shadow II. Spectroscopic separation of dark cloud's light, and results
• Probing the EBL evolution at high redshift using GRBs detected with the Fermi-LAT

Cited by in corpus (6)

• Blazars at the Cosmic Dawn
• TeV-peaked candidate BL Lac objects
• Multiwavelength Study of High-Redshift Blazars
• Extragalactic background light models and GeV-TeV observation of blazars
• NuSTAR Observations and multi-wavelength modeling of the high-redshift BL Lac Object 4FGL J2146.5-1344
• Studies of Extragalactic Background Light with TeV BL Lac Objects