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Issue A&A
Volume 456, Number 3, September IV 2006
Page(s) 929 - 939
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20054153



A&A 456, 929-939 (2006)
DOI: 10.1051/0004-6361:20054153

VLT/ISAAC spectra of the H$\beta$ region in intermediate-redshift quasars

II. Black hole mass and Eddington ratio
J. W. Sulentic1, P. Repetto2, 3, G. M. Stirpe4, P. Marziani2, D. Dultzin-Hacyan3 and M. Calvani2

1  Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487, USA
    e-mail: giacomo@merlot.astr.ua.edu
2  Osservatorio Astronomico di Padova, INAF, Vicolo dell' Osservatorio 5, 35122 Padova, Italy
    e-mail: [marziani;calvani]@pd.astro.it
3  Instituto de Astronomía, UNAM, Aptdo. Postal 70-264, México, D. F. 04510, México
    e-mail: [prepetto;deborah]@astroscu.unam.mx
4  Osservatorio Astronomico di Bologna, INAF, via Ranzani 1, 40127 Bologna, Italy
    e-mail: stirpe@bo.astro.it

(Received 5 September 2005 / Accepted 16 June 2006)

Abstract
We derive black hole masses for a sample of about 300 AGNs in the redshift range 0 < z < 2.5. We use the same virial velocity measure (FWHM H $\beta_{\rm BC}$) for all sources which represents a significant improvement over previous studies. We review methods and caveats for determining AGN black hole masses via the virial assumption for motions in the gas producing low ionization broad emission lines. We derive a corrected FWHM(H $\beta_{\rm BC}$) measure for the broad component of H$\beta$ that better estimates the virialized line emitting component by comparing our FWHM measures with a sample of reverberated sources with H$\beta$ radial velocity dispersion measures. We also consider the FWHM of the FeII$\lambda$ 4570 blend as a potential alternative velocity estimator. We find a range of black hole mass between $\log $ $M_{\rm BH}$ ~ 6.0-10.0, where $M_{\rm BH}$ is in solar masses. Estimates using corrected FWHM(H$\beta$), as well as FWHM(FeII) measures, reduce the number of sources with $\log $ $M_{\rm BH}$ > 9.5 and suggest that extremely large $M_{\rm BH}$ values ($\log $ $M_{\rm BH}$ $\ga$ 10) may not be realistic. Derived $L/L_{\rm Edd}$ values show no evidence for a significant population of super-Eddington radiators especially after correction is made for sources with extreme orientation to our line of sight. Sources with FWHM(H $\beta_{\rm BC}$) $\la$ 4000 km s-1 show systematically higher $L/L_{\rm Edd}$ and lower $M_{\rm BH}$ values than broader lined AGNs (including almost all radio-loud sources).


Key words: galaxies: quasars: emission lines -- galaxies: quasars: general -- line: profiles -- black hole physics



© ESO 2006

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