The Spatial Clustering of ROSAT All-Sky Survey Active Galactic Nuclei. IV. More Massive Black Holes Reside in More Massive Dark Matter Halos

This is the fourth paper in a series that reports on our investigation of the clustering properties of active galactic nuclei (AGNs) identified in the ROSAT All-Sky Survey and Sloan Digital Sky Survey (SDSS). In this paper we investigate the cause of the X-ray luminosity dependence of the clustering of broad-line, luminous AGNs at 0.16\lt z\lt 0.36. We fit the Hα line profile in the SDSS spectra for all X-ray and optically selected broad-line AGNs, determine the mass of the supermassive black hole (SMBH), {M}_{BH}, and infer the accretion rate relative to Eddington (L/{L}_{EDD}). Since {M}_{BH} and L/{L}_{EDD} are correlated, we create AGN subsamples in one parameter while maintaining the same distribution in the other parameter. In both the X-ray and optically selected AGN samples, we detect a weak clustering dependence with {M}_{BH} and no statistically significant dependence on L/{L}_{EDD}. We find a difference of up to 2.7σ when comparing the objects that belong to the 30% least and 30% most massive {M}_{BH} subsamples, in that luminous broad-line AGNs with more massive black holes reside in more massive parent dark matter halos at these redshifts. These results provide evidence that higher accretion rates in AGNs do not necessarily require dense galaxy environments, in which more galaxy mergers and interactions are expected to channel large amounts of gas onto the SMBH. We also present semianalytic models that predict a positive {M}_{DMH} dependence on {M}_{BH}, which is most prominent at {M}_{BH}∼ {10}^8-9 {M}_⊙ .