Measurement of the EBL spectral energy distribution using the VHE gamma-ray spectra of H.E.S.S. blazars

TL;DR

This paper presents an EBL spectral energy distribution measurement using VHE gamma-ray spectra from H.E.S.S. blazars, detecting the EBL signature with high significance and providing insights into the universe's transparency to gamma-rays.

Contribution

It offers a model-independent measurement of the EBL SED based solely on H.E.S.S. data, utilizing gamma-ray absorption features in blazar spectra.

Findings

EBL signature detected at 9.5 sigma significance

EBL intensity measured across different spectral bands

Gamma-ray horizon characterized

Abstract

Very high-energy gamma-rays (VHE, E>100 GeV) propagating over cosmological distances can interact with the low-energy photons of the extragalactic background light (EBL) and produce electron-positron pairs. The transparency of the universe to VHE gamma-rays is then directly related to the spectral energy distribution (SED) of the EBL. The observation of features in the VHE energy spectra of extragalactic sources allows the EBL to be measured, which otherwise is very difficult to determine. An EBL-model independent measurement of the EBL SED with the H.E.S.S. array of Cherenkov telescopes is presented. It is obtained by extracting the EBL absorption signal from the reanalysis of high-quality spectra of blazars. From H.E.S.S. data alone the EBL signature is detected at a significance of 9.5 sigma, and the intensity of the EBL obtained in different spectral bands is presented together with the associated gamma-ray horizon.