Do quasar broad-line velocity widths add any information to virial black hole mass estimates?

Abstract

We examine how much information measured broad-line widths add to virial BH mass estimates for flux limited samples of quasars. We do this by comparing the BH mass estimates to those derived by randomly reassigning the quasar broad-line widths to different objects and re-calculating the BH mass. For 9000 BH masses derived from the H_beta line we find that the distributions of original and randomized BH masses in the M_BH-redshift plane and the M_BH-luminosity plane are formally identical. A 2D KS test does not find a difference at >90% confidence. For the MgII line (32000 quasars) we do find very significant differences between the randomized and original BH masses, but the amplitude of the difference is still small. The difference for the CIV line (14000 quasars) is 2-3sigma and again the amplitude of the difference is small. Subdividing the data into redshift and luminosity bins we find that the median absolute difference in BH mass between the original and randomized data is 0.025, 0.01 and 0.04 dex for H_beta, MgII and CIV respectively. The maximum absolute difference is always <=0.1 dex. We investigate whether our results are sensitive to corrections to MgII virial masses (e.g. Onken & Kollmeier 2008). These corrections do not influence our results. Moreover, the mass residual - Eddington ratio correlation discussed by Onken & Kollmeier is more directly attributable to the slope of the relation between H_beta and MgII line width. Our results imply that the measured quasar broad-line velocity widths provide little extra information, after allowing for the mean velocity width. In this case virial estimates are equivalent to M_BH L^alpha, with L/L_edd L^(1-alpha) (with alpha~0.5). This leaves an unanswered question of why the accretion efficiency changes with luminosity in just the right way to keep the mean broad-line widths fixed as a function of luminosity. (abridged)

9 Pages, 9 figures. Accepted by Astrophysical Journal

References in corpus (16)

• Biases in Virial Black Hole Masses: An SDSS Perspective
• The Sloan Digital Sky Survey Quasar Catalog IV. Fifth Data Release
• The Black Hole Mass, Stellar M/L, and Dark Halo in M87
• The effect of radiation pressure on virial black hole mass estimates and the case of Narrow Line Seyfert 1 galaxies
• The Radio-Loud Fraction of Quasars is a Strong Function of Redshift and Optical Luminosity
• The Star-Forming Torus and Stellar Dynamical Black Hole Mass in the Seyfert 1 Nucleus of NGC3227
• Black-Hole Mass and Growth Rate at High Redshift
• The 2dF-SDSS LRG and QSO Survey: The spectroscopic QSO catalogue
• Are the black hole masses in Narrow Line Seyfert 1 galaxies actually small?
• Mass Functions of the Active Black Holes in Distant Quasars from the Sloan Digital Sky Survey Data Release 3
• Circumnuclear Gas in Seyfert 1 Galaxies: Morphology, Kinematics, and Direct Measurement of Black Hole Masses
• Orientation dependency of broad-line widths in quasars and consequences for black-hole mass estimation
• The Black Hole Mass of NGC 4151: Comparison of Reverberation Mapping and Stellar Dynamical Measurements
• VLT/ISAAC Spectra of the H-beta Region in Intermediate-Redshift Quasars II. Black Hole Mass and Eddington Ratio
• An Improved Method for Using MgII to Estimate Black Hole Masses in Active Galactic Nuclei
• Constraining the quasar population with the broad-line width distribution

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