Cosmic evolution of the helium and oxygen abundances in type 2 Active Galactic Nuclei: Helium-loud AGNs

O. L. Dors, M. Armah, G. F. Hägele +14

We derive the helium and oxygen abundances in the Narrow Line Regions (NLRs) of 84 Active Galactic Nuclei (AGNs) spanning two redshift ranges: 65 objects at $z<0.2$ and 19…