Quasar host galaxies and the MSMBH–σ* relation

We analyze the emission line profiles detected in deep optical spectra of quasars to derive the mass of their supermassive black holes (SMBH) following the single-epoch virial method. Our sample consists in six radio-loud (RL) quasars and four radio-quiet (RQ) quasars. We carefully fit a broad and narrow Gaussian component for each emission line in both the H beta (10 objects) and Ha regions (5 objects). A very good agreement of the derived SMBH masses, MSMBH, is found using the fitted broad H beta and H alpha emission lines. We compare our MSMBH results with those found by previous studies. We study the relationship between the MSMBH of the quasar and the stellar velocity dispersion, sigma*, of the host galaxy. We use the measured MSMBH and sigma* to investigate the MSMBH–σ* relation for both the RL and radio-quiet subsamples. Besides the scatter, we find a good agreement between radioquiet quasars and AGN vertical bar quiescent galaxies and between RL quasars and AGN. Our analysis does not support the hypothesis of using sigma([O III] lambda 5007) as a surrogate for stellar velocity dispersions in high-mass, high-luminosity quasars. We also investigate the relationship between the 5 GHz radio-continuum luminosity, L-5 (GHz), of the quasar host galaxy with both MSMBH and sigma*. We do not find any correlation between L-5 GHz and MSMBH, although we observe a trend that galaxies with larger stellar velocity dispersions have larger L-5 GHz. Using the results of our fitting for the narrow emission lines of [O III] lambda 5007 and [N II] lambda 6583 we estimate the gas-phase oxygen abundance of six quasars, being sub-solar in all cases.