We analyze the emission line profiles detected in deep optical spectra of quasars to derive the mass of their super-massive black holes (SMBH) following the single-epoch virial method. Our sample consists in 6 radio-loud quasars and 4 radio-quiet quasars. We carefully fit a broad and narrow Gaussian component for each emission line in both the H$beta$ (10 objects) and H$alpha$ regions (5 objects). A very good agreement of the derived SMBH masses, $M_{rm SMBH}$, is found using the fitted broad H$beta$ and H$alpha$ emission lines. We compare our $M_{rm SMBH}$ results with those found by previous studies. We study the relationship between the $M_{rm SMBH}$ of the quasar and the stellar velocity dispersion, $sigma_{*}$, of the host galaxy. We use the measured $M_{rm SMBH}$ and $sigma_{*}$ to investigate the $M_{rm SMBH}$ - $sigma_{*}$ relation for both the radio-loud and radio-quiet subsamples. Besides the scatter, we find a good agreement between radio-quiet quasars and AGN+quiescent galaxies and between radio-loud 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, $L_{rm~5,GHz}$, of the quasar host galaxy with both $M_{rm SMBH}$ and $sigma_{*}$. We do not find any correlation between $L_{rm 5,GHz}$ and $M_{rm SMBH}$, although we observe a trend that galaxies with larger stellar velocity dispersions have larger $L_{rm 5,GHz}$. 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.
تحميل البحث