FeiiEmission in 14 Low‐Redshift Quasars. I. Observations

We present the spectra of 14 quasars with a wide coverage of rest wavelengthsfrom 1000 to 7300 A. The redshift ranges from z = 0.061 to 0.555 and theluminosity from M_{B} = -22.69 to -26.32. We describe the procedure ofgenerating the template spectrum of Fe II line emission from the spectrum of anarrow-line Seyfert 1 galaxy I Zw 1 that covers two wavelength regions of2200-3500 A and 4200-5600 A. Our template Fe II spectrum is semi-empirical inthe sense that the synthetic spectrum calculated with the CLOUDYphotoionization code is used to separate the Fe II emission from the Mg IIline. The procedure of measuring the strengths of Fe II emission lines istwofold; (1) subtracting the continuum components by fitting models of thepower-law and Balmer continua in the continuum windows which are relativelyfree from line emissions, and (2) fitting models of the Fe II emission based onthe Fe II template to the continuum-subtracted spectra. From 14 quasars, weobtained the Fe II fluxes in five wavelength bands, the total flux of Balmercontinuum, and the fluxes of Mg II, Halpha, and other emission lines, togetherwith the full width at half maxima (FWHMs) of these lines. Regression analysiswas performed by assuming a linear relation between any two of thesequantities. Eight correlations were found with a confidence level higher than99%. The fact that six of these eight are related to FWHM or M_{BH} may implythat M_{BH} is a fundamental quantity that controls Gamma or the spectralenergy distribution (SED) of the incident continuum, which in turn controls theFe II emission. Furthermore, it is worthy of noting that Fe II(O1)/Fe II(U1) isfound to tightly correlate with Fe II(O1)/Mg II, but not with Fe II(U1)/Mg II.Comment: 50 pages, 10 figures, accepted for publication in Ap