BROAD-LINE REGION PHYSICAL CONDITIONS IN EXTREME POPULATION A QUASARS: A METHOD TO ESTIMATE CENTRAL BLACK HOLE MASS AT HIGH REDSHIFT

Journal Article · Thu Sep 20 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/757/1/62· OSTI ID:22092256

Negrete, C. Alenka; Dultzin, Deborah ^[1]; Marziani, Paola ^[2]

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1. Instituto de Astonomia, Universidad Nacional Autonoma de Mexico (Mexico)
2. INAF, Astronomical Observatory of Padova, I-35122 Padova (Italy)

We describe a method for estimating physical conditions in the broad-line region (BLR) for a significant subsample of Seyfert 1 nuclei and quasars. Several diagnostic ratios based on intermediate (Al III {lambda}1860, Si III] {lambda}1892) and high (C IV {lambda}1549, Si IV {lambda}1397) ionization lines in the UV spectra of quasars are used to constrain density, ionization, and metallicity of the emitting gas. We apply the method to two extreme Population A quasars-the prototypical NLSy1 I Zw 1 and higher z source SDSS J120144.36+011611.6. Under assumptions of spherical symmetry and pure photoionization we infer BLR physical conditions: low ionization (ionization parameter <10{sup -2}), high density (10{sup 12}-10{sup 13} cm{sup -3}), and significant metal enrichment. Ionization parameter and density can be derived independently for each source with an uncertainty that is less than {+-}0.3 dex. We use the product of density and ionization parameter to estimate the BLR radius and derive an estimation of the virial black hole mass (M{sub BH}). Estimates of M{sub BH} based on the 'photoionization' analysis described in this paper are probably more accurate than those derived from the mass-luminosity correlations widely employed to compute black hole masses for high-redshift quasars.

• OSTI ID: 22092256
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 757; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALUMINIUM IONS
ASTRONOMY
ASTROPHYSICS
BLACK HOLES
CARBON IONS
CORRELATIONS
DENSITY
GALAXY NUCLEI
LUMINOSITY
MASS
PHOTOIONIZATION
QUASARS
RED SHIFT
SEYFERT GALAXIES
SILICON IONS
ULTRAVIOLET SPECTRA