An FMOS Survey of moderate-luminosity broad-line AGN in COSMOS, SXDS and E-CDF-S

We present near-IR spectroscopy in the J- and H-bands for a large sample of 243 X-ray-selected, moderate-luminosity Type 1 active galactic nuclei (AGNs) in the COSMOS, SXDS, and E-CDF-S survey fields using the multi-object spectrograph Subaru/FMOS. Our sample covers the redshift range 0.5 less than or similar to z less than or similar to 3.0 and X-ray luminosity range of 10(43) less than or similar to L[2-10keV] less than or similar to 10(45) erg s(-1). We provide emission-line properties and derived virial black hole mass estimates, bolometric luminosities, and Eddington ratios, based on H alpha (211), H beta (63), and Mg II (4). We compare line widths, luminosities, and black hole mass estimates from H alpha and H beta, and augment these with commensurate measurements of Mg II and C IV detected in optical spectra. We demonstrate the robustness of using H alpha, H beta, and Mg II as reliable black hole mass estimators for high-z moderate-luminosity AGNs, while the use of C IV is prone to large uncertainties (greater than or similar to 0.4 dex). We extend a recently proposed correction based on the C IV blueshift to lower luminosities and black hole masses. While our sample shows an improvement in their C IV black hole mass estimates, the deficit of high blueshift sources reduces its overall importance for moderate-luminosity AGNs compared to the most luminous quasars. In addition, we revisit luminosity correlations between L-bol, L[2-10keV], L-[O III], L-5100, and L-H alpha and find them to be consistent with a simple empirical model, based on a small number of well-established scaling relations. Finally, we highlight our highest redshift AGN, CID 781, at z = 4.6, which has the lowest black hole mass (similar to 10(8) M-circle dot) among current near-IR samples at this redshift and is in a state of fast growth.