The Relationship between Luminosity and Broad-Line Region Size in Active Galactic Nuclei

By S. Kaspi, D. Maoz, H. Netzer, B. Peterson, M. Vestergaard, B. Jannuzi. 2005

689 citations recorded by the source corpus.

We reinvestigate the relationship between the characteristic broad-line region size (RBLR) and the Balmer emission-line, X-ray, UV, and optical continuum luminosities. Our study makes use of the best available determinations of RBLR for a large number of active galactic nuclei (AGNs) from Peterson et al. Using their determinations of RBLR for a large sample of AGNs and two different regression methods, we investigate the robustness of our correlation results as a function of data subsample and regression technique. Although small systematic differences were found depending on the method of analysis, our results are generally consistent. Assuming a power-law relation RBLR ∝ Lα, we find that the mean best-fitting α is about 0.67 ± 0.05 for the optical continuum and the broad Hβ luminosity, about 0.56 ± 0.05 for the UV continuum luminosity, and about 0.70 ± 0.14 for the X-ray luminosity. We also find an intrinsic scatter of ~40% in these relations. The disagreement of our results with the theoretical expected slope of 0.5 indicates that the simple assumption of all AGNs having on average the same ionization parameter, BLR density, column density, and ionizing spectral energy distribution is not valid and there is likely some evolution of a few of these characteristics along the luminosity scale.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4c389947d9e0c94ae9b246f5314962319cd0ce44

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In Astronomy and Astrophysics

1. D. M. Alexander
2. P. Hopkins
3. L. Hernquist
4. H. Netzer
5. Jenny E. Greene
6. Luis C. Ho
7. R. Hickox
8. W. N. Brandt

Citations in the corpus

• What broad emission lines tell us about how active galactic nuclei work (2009, methodology): “This is supported by reverberation mapping estimates of the effective radii of BLRs (Koratkar & Gaskell, 1991c; Kaspi et al., 2000, 2005; Bentz et al., 2006, 2009a).”
• THE LICK AGN MONITORING PROJECT: BROAD-LINE REGION RADII AND BLACK HOLE MASSES FROM REVERBERATION MAPPING OF Hβ (2009, background): “L relationship (Koratkar & Gaskell 1991; Kaspi et al. 2000, 2005; Bentz et al. 2006a, 2009a).”
• Biases in Virial Black Hole Masses: An SDSS Perspective (2007, background): “However, reverberation mapping data has revealed a correlation between BLR sizeR and luminosity (Kaspi et al. 2000, 2005), which allows us to estimate BH masses based on single-epoch spectra.”
• The Effect of Radiation Pressure on Virial Black Hole Mass Estimates and the Case of Narrow-Line Seyfert 1 Galaxies (2008, background): “The radiusluminosity relation discovered by Kaspi et al. (2000) shows that continuum luminosity can be used as a proxy forRBLR (Kaspi et al. 2000, 2005; Bentz et al. 2006b).”
• AN ALTERNATIVE APPROACH TO MEASURING REVERBERATION LAGS IN ACTIVE GALACTIC NUCLEI (2010, background): “Second, reverberation studies have established a tight empirical relationship between the BLR size and the AGN continuum luminosity (Kaspi et al. 1996; Kaspi et al. 2000, 2005; Bentz et al. 2006, 2009) that allows us to use the luminosity as a surrogate for the BLR size in eq.”
• THE RADIATIVE EFFICIENCY OF ACCRETION FLOWS IN INDIVIDUAL ACTIVE GALACTIC NUCLEI (2010, methodology): “We use the luminosity radius relation of Kaspi et al. (2005) to compute the BLR radius RBLR, but with Lopt = νLν measured at 4861Å instead of 5100Å.”
• REVERBERATION MAPPING MEASUREMENTS OF BLACK HOLE MASSES IN SIX LOCAL SEYFERT GALAXIES (2010, background): “L relationship (Kaspi et al. 2000, 2005; Bentz et al. 2006, 2009b), which provides the capability to estimate BH masses from a single spectrum of an AGN (Wandel et al. 1999).”
• RELATIONS BETWEEN CENTRAL BLACK HOLE MASS AND TOTAL GALAXY STELLAR MASS IN THE LOCAL UNIVERSE (2015, methodology): “The average gas velocity is inferred from the width of a broad emission line (typically Hβ) and the radius of the BLR is estimated from the radius-luminosity relation defined by reverberation-mapped AGN (e.g., Kaspi et al. 2005; Bentz et al. 2013).”
• THE MEGAMASER COSMOLOGY PROJECT. III. ACCURATE MASSES OF SEVEN SUPERMASSIVE BLACK HOLES IN ACTIVE GALAXIES WITH CIRCUMNUCLEAR MEGAMASER DISKS (2010, methodology): “…maser and viral BH masses as compared with the expected accuracy for the virial method is partly caused by the larger intrinsic scatter in the L(2−10kev) −RBLR correlation which we used here than that in the more generally used λLλ(5100Å)−RBLR correlation (e.g. Kaspi et al. 2005) in the optical.”
• THE MAN BEHIND THE CURTAIN: X-RAYS DRIVE THE UV THROUGH NIR VARIABILITY IN THE 2013 ACTIVE GALACTIC NUCLEUS OUTBURST IN NGC 2617 (2013, background): “Reverberation mapping studies ofthe Hβ emission line in local AGN indicate that there is a tight correlation between the AGN continuum linosity at 5100 Å andRBLR (Kaspi et al. 2005; Bentz et al. 2009, 2013; Zu et al. 2011).”
• ESTIMATING BLACK HOLE MASSES IN ACTIVE GALACTIC NUCLEI USING THE Mg ii λ2800 EMISSION LINE (2009, background): “Second, the size of the BLR scales with the continuum luminosity (Kaspi et al. 2000, 2005), approximately as R ∝ L0.”
• Cosmic Evolution of Black Holes and Spheroids. II. Scaling Relations at z = 0.36 (2007, background): “The width of the line provides the velocity scale, while the nuclear continuum luminosity provides the size via the empirical correlation observed for the local reverberation-mapped sample (Wandel et al. 1999; Kaspi et al. 2000, 2005; Bentz et al. 2006a).”
• Measuring the Masses of Supermassive Black Holes (2014, background): “A refinement of the database led to a somewhat shallower slope (Kaspi et al. 2005), but it was only when contamination of the luminosity by hostgalaxy starlight was accounted for (Bentz et al. 2006a, 2009b, 2013) that the slope was close to the näıve photoionization prediction.”
• Some Aspects of Measurement Error in Linear Regression of Astronomical Data (2007, neutral): “L relationship, e.g., Kaspi et al. 2005).”
• Cosmic Evolution of Black Holes and Spheroids. III. The MBH-σ* Relation in the Last Six Billion Years (2008, methodology): “In paper II, for Seyfert galaxies with similar luminosity, we compared MBH estimates based on the size-luminosity relation of Kaspi et al. (2005) with new estimates based on the revised size-luminosity relations of Bentz et al. (2006a), after correcting for host galaxy contamination using HST…”
• Physical Properties of 15 Quasars at z ≳ 6.5 (2017, background): “Several studies of this kind have shown that the continuum luminosity and RBLR of AGN in the local universe correlate strongly (e.g. Kaspi et al. 2005, Bentz et al. 2013).”
• Reverberation Mapping of High-Luminosity Quasars: First Results (2006, methodology): “We have used the two methods that are described in detail in Kaspi et al. (2005): (1) the FITEXY from Press et al. (1992, p. 660), which is based on an iterative process tominimize 2 and inwhich we adopted the Tremaine et al. (2002) procedure to account for the intrinsic scatter in the data, and…”