Black hole mass estimates in quasars. A comparative analysis of high- and low-ionization lines

DOI: 
10.1051/0004-6361/201935265
Publication date: 
01/07/2019
Main author: 
Marziani, P.
IAA authors: 
del Olmo, A.
Authors: 
Marziani, P.;del Olmo, A.;Martínez-Carballo, M. A.;Martínez-Aldama, M. L.;Stirpe, G. M.;Negrete, C. A.;Dultzin, D.;D'Onofrio, M.;Bon, E.;Bon, N.
Journal: 
Astronomy and Astrophysics
Refereed: 
Yes
Publication type: 
Article
Volume: 
627
Pages: 
A88
Abstract: 
Context. The inter-line comparison between high- and low-ionization emission lines has yielded a wealth of information on the structure and dynamics of the quasar broad line region (BLR), including perhaps the earliest unambiguous evidence in favor of a disk + wind structure in radio-quiet quasars. <BR /> Aims: We carried out an analysis of the C IVλ1549 and Hβ line profiles of 28 Hamburg-ESO high-luminosity quasars and of 48 low-z, low-luminosity sources in order to test whether the width of the high-ionization line C IVλ1549 could be correlated with Hβ and be used as a virial broadening estimator. <BR /> Methods: We analyze intermediate- to high-S/N, moderate-resolution optical and near-infrared (NIR) spectra covering the redshifted C IVλ1549 and Hβ over a broad range of luminosity log L ̃ 44 - 48.5 [erg s<SUP>-1</SUP>] and redshift (0 - 3), following an approach based on the quasar main sequence. <BR /> Results: The present analysis indicates that the line width of C IVλ1549 is not immediately offering a virial broadening estimator equivalent to Hβ. At the same time a virialized part of the BLR appears to be preserved even at the highest luminosities. We suggest a correction to FWHM(C IVλ1549) for Eddington ratio (using the C IVλ1549 blueshift as a proxy) and luminosity effects that can be applied over more than four dex in luminosity. <BR /> Conclusions: Great care should be used in estimating high-L black hole masses M<SUB>BH</SUB> from C IVλ1549 line width. However, once a corrected FWHM C IVλ1549 is used, a C IVλ1549-based scaling law can yield unbiased M<SUB>BH</SUB> values with respect to the ones based on Hβ with sample standard deviation ≈0.3 dex.
Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069440905&doi=10.1051%2f0004-6361%2f201935265&partnerID=40&md5=a471869f1f2e6445130b7d2896df8f87
ADS Bibcode: 
2019A&A...627A..88M
Keywords: 
quasars: general;quasars: emission lines;quasars: supermassive black holes;line: profiles;ISM: jets and outflows;Astrophysics - Astrophysics of Galaxies;Astrophysics - Cosmology and Nongalactic Astrophysics