Detecting a unique EBL signature with TeV gamma rays

TL;DR

This paper explores the potential of using TeV gamma-ray spectra from blazars to detect spectral signatures caused by the extragalactic background light, which could reveal the EBL's spectral shape and density variations.

Contribution

It introduces a method to identify spectral breaks in TeV blazar spectra as signatures of EBL absorption, providing a new observational approach to constrain EBL properties.

Findings

Spectral breaks at 1 TeV can indicate EBL density variations.

Detection sensitivity depends on blazar redshift and EBL spectral shape.

Non-detection constrains EBL spectrum models.

Abstract

We discuss prospects for detecting a spectral break in gamma-ray spectra of blazars due to the extragalactic background light (EBL) density falling off between the near and mid-IR. A measurable spectral change in the TeV spectra at 1 TeV could arise from a rapid or slow drop in the EBL density above ~1 micron. This effect is mediated by the ratio of the near to mid-IR density of EBL. A detection of such a spectral feature could become a clear signature of EBL absorption. A non-detection would give a strong observational constraint to the shape of the EBL spectrum. We present calculations estimating the sensitivity of TeV telescopes for detecting such a break for blazar observations at different redshifts.