A Universal 1.5 GeV Gamma-Ray Line in Active Galactic Nuclei

Shi-Ju Kang, Yue Yin, Yong-Gang Zheng +1

We report the detection of a gamma-ray spectral line at approximately 1.5 GeV in three active galactic nuclei (AGN) using 17 years of Fermi-LAT observations. The sample includes bo…