EBL studies with ground-based VHE gamma-ray detectors: Current status and potential of next-generation instruments

TL;DR

This paper reviews how ground-based VHE gamma-ray detectors have constrained the extragalactic background light (EBL) and discusses how future instruments could enhance these measurements, improving our understanding of the universe's emission history.

Contribution

It provides a summary of current constraints on EBL from VHE gamma-ray observations and explores the potential improvements with next-generation ground-based VHE instruments.

Findings

Current VHE observations constrain EBL density, especially in near-infrared.

Next-generation instruments could significantly improve EBL measurements.

VHE gamma-ray attenuation offers an indirect method to study cosmic background light.

Abstract

The diffuse meta-galactic radiation field at ultraviolet to infrared wavelengths - commonly labeled extragalactic background light (EBL) - contains the integrated emission history of the universe. Difficult to access via direct observations, indirect constraints on its density can be derived through observations of very-high energy (VHE; E>100 GeV) gamma-rays from distant sources: the VHE photons are attenuated via pair-production with the low energy photons from the EBL, leaving a distinct imprint in the VHE spectra measured on earth. Discoveries made with current-generation VHE observatories like H.E.S.S., MAGIC and VERITAS enabled strong constraints on the density of the EBL, especially in the near-infrared. Here, the constrains on the EBL density from such ground based VHE observations will be briefly reviewed and the potential of the next-generation instruments to improve on these limits will be discussed.