Revisiting the Indication for a low opacity Universe for very high energy gamma-rays
Abstract
Very high energy (VHE, energy >~ 100 GeV) {\gamma}-rays undergo pair production with photons of the extragalactic background light (EBL). Thus, the intrinsic {\gamma}-ray flux of cosmological sources is attenuated and the Universe should be opaque to {\gamma}-rays above a redshift dependent energy. Recently, an indication has been found that the Universe is more transparent than predicted by a lower-limit EBL model. Here, this indication is confronted with additional VHE {\gamma}-ray spectra and different EBL models. Depending on the model for the opacity, the indication persist between a ~2.6 {\sigma} and ~4.3 {\sigma} confidence level.
Keywords
Cite
@article{arxiv.1211.6405,
title = {Revisiting the Indication for a low opacity Universe for very high energy gamma-rays},
author = {Manuel Meyer and Dieter Horns and Martin Raue},
journal= {arXiv preprint arXiv:1211.6405},
year = {2013}
}
Comments
Contributed to the 8th Patras Workshop on Axions, WIMPs and WISPs, Chicago, July 18-22, 2012, added further discussion and references for cascade emission, main conclusion unchanged