Speaker
Description
The diffuse Extragalactic Background Light (EBL) consists of the total emitted light from all stars throughout the history of the Universe. Through pair-production with EBL photons, Very High Energy (VHE) gamma-rays are attenuated as they travel through the Universe, leaving a unique mark on the detected spectra of VHE gamma-ray sources. Due to the relatively small EBL optical depth, most studies attempting to measure the EBL through this phenomena have used higher redshift sources. M87 is a nearby (z ~ 0.0042) radio galaxy which has been extensively studied at numerous wavelengths, and is a known source of VHE gamma-rays. In this study we attempt to measure the local EBL through its attenuation of the TeV gamma-ray spectrum of M87 during its high-states using data obtained with the High Energy Stereoscopic System (H.E.S.S). We find that an EBL-attenuated spectrum is preferred at the ~2.5 σ level to a pure power-law.
