NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-21 T18:15:33 PDT
Help | Comment | NED Home

For refcode 2013ApJ...771...31N:
Retrieve 13 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
2013ApJ...771...31N Reverberation and Photoionization Estimates of the Broad-line Region Radius in Low-z Quasars Negrete, C. A.; Dultzin, Deborah; Marziani, Paola; Sulentic, Jack W. Abstract. Black hole mass estimation in quasars, especially at high redshift, involves the use of single-epoch spectra with signal-to-noise ratio and resolution that permit accurate measurement of the width of a broad line assumed to be a reliable virial estimator. Coupled with an estimate of the radius of the broad-line region (BLR) this yields the black hole mass M_BH_. The radius of the BLR may be inferred from an extrapolation of the correlation between source luminosity and reverberation-derived r_BLR_ measures (the so-called Kaspi relation involving about 60 low-z sources). We are exploring a different method for estimating r_BLR_ directly from inferred physical conditions in the BLR of each source. We report here on a comparison of r_BLR_ estimates that come from our method and from reverberation mapping. Our "photoionization" method employs diagnostic line intensity ratios in the rest-frame range 1400-2000 A (Al III lambda1860/Si III] lambda1892, C IV lambda1549/Al III lambda1860) that enable derivation of the product of density and ionization parameter with the BLR distance derived from the definition of the ionization parameter. We find good agreement between our estimates of the density, ionization parameter, and r_BLR_ and those from reverberation mapping. We suggest empirical corrections to improve the agreement between individual photoionization-derived r_BLR_ values and those obtained from reverberation mapping. The results in this paper can be exploited to estimate M_BH_ for large samples of high-z quasars using an appropriate virial broadening estimator. We show that the width of the UV intermediate emission lines are consistent with the width of Hbeta, thereby providing a reliable virial broadening estimator that can be measured in large samples of high-z quasars. Key words: black hole physics, galaxies: active, quasars: emission lines, quasars: general
Retrieve 13 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home