Constraining Extragalactic Background Light From TeV Blazars

TL;DR

This paper establishes upper limits on the extragalactic background light (EBL) by analyzing TeV blazar spectra, constraining high EBL density models using Fermi and VHE observations.

Contribution

It introduces a method to constrain EBL density using VHE and Fermi spectra, ruling out high EBL models based on blazar observations.

Findings

Upper limits on EBL are compatible with most models.

High EBL density models are inconsistent with TeV blazar data.

VHE intrinsic photon index cannot be harder than Fermi index.

Abstract

Our goal is to research the upper limits on the extragalactic background light (EBL). The upper limits on the extragalactic background light (EBL), using the Fermi and very high energy (VHE) spectra recently observed in TeV blazars, are presented. We use an assumption that the VHE intrinsic photon index cannot be harder than the Fermi index measured by the Fermi-LAT. Totally, these upper limits on the EBL are compatible with ones given by most of EBL models. However, the models of high EBL density are denied by TeV blazars.