ESTIMATING BLACK HOLE MASSES IN ACTIVE GALACTIC NUCLEI USING THE Mg ii λ2800 EMISSION LINE

By Jian-Guo Wang, Xiao-bo Dong, Ting-gui Wang, Luis C. Ho, W. Yuan, Huiyuan Wang, Kai Zhang, Shaohua Zhang, Hongyan Zhou. 2009

163 citations recorded by the source corpus.

We investigate the relationship between the linewidths of broad Mg ii λ2800 and Hβ in active galactic nuclei (AGNs) to refine them as tools to estimate black hole (BH) masses. We perform a detailed spectral analysis of a large sample of AGNs at intermediate redshifts selected from the Sloan Digital Sky Survey, along with a smaller sample of archival ultraviolet spectra for nearby sources monitored with reverberation mapping (RM). Careful attention is devoted to accurate spectral decomposition, especially in the treatment of narrow-line blending and Fe ii contamination. We show that, contrary to popular belief, the velocity width of Mg ii tends to be smaller than that of Hβ, suggesting that the two species are not cospatial in the broad-line region. Using these findings and recently updated BH mass measurements from RM, we present a new calibration of the empirical prescriptions for estimating virial BH masses for AGNs using the broad Mg ii and Hβ lines. We show that the BH masses derived from our new formalisms show subtle but important differences compared to some of the mass estimators currently used in the literature.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/9653a57e4317e1eb4de2d87b51ec225e3a1e8bd2

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Citations in the corpus

• An expanded Mbh–σ diagram, and a new calibration of active galactic nuclei masses (2010, methodology): “Furthermore, the single-epoch methods of SMBH mass estimation which were calibrated to the RM results would be simi- larly affected (Vestergaard & Peterson 2006; McGill et al. 2008; Wang et al. 2009; Greene, Peng & Ludwig 2010).”
• A CATALOG OF QUASAR PROPERTIES FROM SLOAN DIGITAL SKY SURVEY DATA RELEASE 7 (2010, methodology): “Some quasars show double-peaked narrow lines (such as [OIII] λλ4959,5007, e.g., Liu et al. 2010a; Smith et al. 2009; Wang et al. 2009a), which could be due to either narrow line region kinematics or a merging AGN pair (e.g., Liu et al. 2010b; Shen et al. 2011).”
• Black Hole Growth to z = 2 - I: Improved Virial Methods for Measuring M_BH and L/L_Edd (2012, background): “© 2012 RAS, MNRAS000, 1–23 Measuring MBH & L/LEdd 11 Several studies suggested to useMBH estimators where the exponent of the velocity term differs from 2 (e.g., Greene & Ho 2005; Wang et al. 2009).”