QUASAR HOST GALAXIES AND THE MSMBH–σ* RELATION

Abstract

ABSTRACT 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 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 Hβ (10 objects) and Hα regions (5 objects). A very good agreement of the derived SMBH masses, , is found using the fitted broad Hβ and Hα emission lines. We compare our results with those found by previous studies. We study the relationship between the of the quasar and the stellar velocity dispersion, , of the host galaxy. We use the measured and to investigate the – relation for both the RL and radio-quiet subsamples. Besides the scatter, we find a good agreement between radio-quiet quasars and AGN+quiescent galaxies and between RL quasars and AGN. Our analysis does not support the hypothesis of using σ([O iii] λ5007) 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, , of the quasar host galaxy with both and . We do not find any correlation between and , although we observe a trend that galaxies with larger stellar velocity dispersions have larger . Using the results of our fitting for the narrow emission lines of [O iii] λ5007 and [N ii] λ6583 we estimate the gas-phase oxygen abundance of six quasars, being sub-solar in all cases.