Central Masses and Broad‐Line Region Sizes of Active Galactic Nuclei. II. A Homogeneous Analysis of a Large Reverberation‐Mapping Database

Abstract

We present improved black hole masses for 35 active galactic nuclei (AGNs) based on a complete and consistent reanalysis of broad emission-line reverberation-mapping data. From objects with multiple line measurements, we find that the highest precision measure of the virial product cτ ∆V 2 /G, where τ is the emission-line lag relative to continuum variations and ∆V is the emission-line width, is obtained by using the crosscorrelation function centroid (as opposed to the cross-correlation function peak) for the time delay and the line dispersion (as opposed to full width half maximum) for the line width and by measuring the line width in the variable part of the spectrum. Accurate line-width measurement depends critically on avoiding contaminating features, in particular the narrow components of the emission lines. We find that the precision (or random component of the error) of reverberation-based black hole mass measurements is typically around 30%, comparable to the precision attained in measurement of black hole masses in quiescent galaxies by gas or stellar dynamical methods. Based on results

Spectroscopic Indication of a Centi-Parsec Supermassive Black Hole Binary in the Galactic Center of Ngc 5548

“…We then remove the [O III] doublet using the template and remove the narrow Hβ component using the same template but adjusting its position and intensity to achieve the smoothest broad-line Hβ profile. The obtained flux ratio of narrow Hβ to [O III]λ5007 generally ranges from 0.10 to 0.15, consistent with the previous determinations (Peterson et al 2004;Sergeev et al 2007). After obtaining the broad Hβ line, its integrated flux is calculated over a uniform wavelength window 4714-4933 Å in the rest frame, as in Peterson et al (2002).…”

“…We note that simply from the relation between BLR sizes and AGN 5100 Å luminosity and the virial relation (e.g., Peterson et al 2004;Bentz et al 2013;Simic & Popovic 2016), the Hβ line width is closely correlated to the 5100 Å luminosity. As a result, the periodic continuum variations of NGC5548 certainly lead to periodic changes in Hβ line width.…”

“…Since the 5100 Å continuum of NGC5548 varies periodically, we expect that the line width of the broad Hβ line should also follow such a temporal variation pattern ( ( ) s b µ -F H con 1 4 ), simply from the well-established relationship between the BLR size and AGN 5100 Å luminosity (the R BLR -L relation; e.g., Bentz et al 2013) and the virial relation of the BLR motion (e.g., Peterson & Wandel 1999;Peterson et al 2004;Simic & Popovic 2016). This will contribute to the periodicity of Hβ profiles seen in the above epoch-folding scheme.…”

Detecting Eccentric Supermassive Black Hole Binaries With Pulsar Timing Arrays: Resolvable Source Strategies

“…330-458), but there is still much that we do not understand about these exotic objects. The combination of electromagnetic observations with future detections of gravitational-wave (GW) signals will provide key insights into the nature of compact objects and the role they play in some of the most energetic events in the universe: gamma-ray bursts, active galactic nuclei, quasars, etc. (Soltan 1982;Kormendy & Richstone 1995;Magorrian et al 1998;Janka et al 1999;Gebhardt et al 2000;Hughes & Blandford 2003;Peterson et al 2004;Lee & Ramirez-Ruiz 2007;Hughes 2009;Metzger & Berger 2012;Berger 2013;Berger et al 2013;Piran et al 2013;Tanvir et al 2013). Several large-scale collaborations are working to inaugurate the new field of GW astronomy by targeting a wide variety of potential GW sources.…”

A Survey of Seyfert AGN: Nuclear Gas Disks and Direct Black Hole Mass Estimates

“…Alternatively, the method of reverberation mapping (Peterson et al 2004) can measure M BH in AGN, but because of the unknown broad line region (BLR) geometry and kinematics, questions remain about the potential systematic 178 E. K. S. Hicks et al uncertainties of these estimates. In addition, secondary methods, such as the use of restframe ultraviolet luminosity and emission-line width, which has been shown to correlate with reverberation-mapped M BH (e.g.…”