We present an observed relationship between Eddington ratio ({\lambda}Edd) and optical narrow-emission-line ratio ([N II]{\lambda}6583/H{\alpha}) of X-ray-selected broad-line active galactic nuclei (AGN) 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 {\lambda}Edd and [N II]{\lambda}6583/H{\alpha} ratio at 0.6 < z < 1.7 exhibits a similar anti-correlation distribution of {\lambda}Edd-[N II]{\lambda}6583/H{\alpha} as has been found for local (<z> = 0.036), ultra-hard X-ray selected AGN. The observed distribution implies that there is a consistent relationship from local to z \sim 1.7 which corresponds from the present time to 4 Gyr old. Further study of high redshift low Eddington ratio AGN (log{\lambda}Edd < -2) is necessary to determine fully whether the {\lambda}Edd-[N II]{\lambda}6583/H{\alpha} anti-correlation still holds in high-redshift AGN at low Eddington ratios.
@article{arxiv.1906.04179,
title = {An observational link between AGN Eddington ratio and [NII]{\lambda}6583/Ha at 0.6<z<1.7},
author = {Kyuseok Oh and Yoshihiro Ueda and Masayuki Akiyama and Hyewon Suh and Michael J. Koss and Daichi Kashino and Günther Hasinger},
journal= {arXiv preprint arXiv:1906.04179},
year = {2019}
}
Comments
15 pages, 7 figures, and 2 tables; Accepted for publication in ApJ