An Observational Link between AGN Eddington Ratio and [N ii]λ6583/Hα at 0.6 < z < 1.7

We present an observed relationship between the Eddington ratio (λ _Edd) and the optical narrow-emission-line ratio ([N ii]λ6583/Hα) of X-ray-selected broad-line active galactic nuclei (AGNs) at 0.6 < z < 1.7. We use 27 near-infrared spectra from the Fiber Multi-Object Spectrograph along with 26 sources from the literature. We show that the λ _Edd and [N ii]λ6583/Hα ratio at 0.6 < z < 1.7 exhibits a similar anti-correlation distribution of λ _Edd-[N ii]λ6583/Hα, as has been found for local (), ultra-hard, X-ray-selected AGNs. The observed distribution implies that there is a consistent relationship from local to z ∼ 1.7, which corresponds from the present time to 4 Gyr old. Further study of high-redshift, low-Eddington-ratio AGNs (log λ _Edd < -2) is necessary to determine fully whether the λ _Edd-[N ii]λ6583/Hα anti-correlation still holds in high-redshift AGNs at low Eddington ratios.