Measurement of the extragalactic background light spectral energy distribution with VERITAS

TL;DR

This paper presents a new measurement of the extragalactic background light's spectral energy distribution using gamma-ray observations of 14 blazars by VERITAS, covering wavelengths from 0.56 to 56 micrometers, consistent with galaxy-based lower limits.

Contribution

It provides an EBL SED measurement independent of models, based on gamma-ray spectra of blazars, covering a broad wavelength range.

Findings

EBL SED measurement agrees with galaxy-based lower limits.

Spectral range covered is 0.56--56 μm.

Measurement is independent of existing EBL models.

Abstract

The extragalactic background light (EBL), a diffuse photon field in the optical and infrared range, is a record of radiative processes over the Universe's history. Spectral measurements of blazars at very high energies ($>$100 GeV) enable the reconstruction of the spectral energy distribution (SED) of the EBL, as the blazar spectra are modified by redshift- and energy-dependent interactions of the gamma-ray photons with the EBL. The spectra of 14 VERITAS-detected blazars are included in a new measurement of the EBL SED that is independent of EBL SED models. The resulting SED covers an EBL wavelength range of 0.56--56 $\mu$m, and is in good agreement with lower limits obtained by assuming that the EBL is entirely due to radiation from cataloged galaxies.