What Does the Virial Coefficient of the \Hb Broad-Line Region Depend On?
Abstract
We combine our dynamical modeling black hole mass measurements from the Lick AGN Monitoring Project 2016 sample with measured cross-correlation time lags and line widths to recover individual scale factors, f, used in traditional reverberation mapping analyses. We extend our sample by including prior results from Code for AGN Reverberation and Modeling of Emission Lines (caramel) studies that have utilized our methods. Aiming to improve the precision of black hole mass estimates, as well as uncover any regularities in the behavior of the broad-line region (BLR), we search for correlations between f and other AGN/BLR parameters. We find (i) evidence for a correlation between the virial coefficient log10(fmean,{\sigma}) and black hole mass, (ii) marginal evidence for a similar correlation between log10(frms,{\sigma}) and black hole mass, (iii) marginal evidence for an anti-correlation of BLR disk thickness with log10(fmean,FWHM)and log10(frms,FWHM), and (iv) marginal evidence for an anti-correlation of inclination angle with log10(fmean,FWHM), log10(frms,{\sigma}), and log10(fmean,{\sigma}). Lastly, we find marginal evidence for a correlation between line-profile shape, when using the root-meansquare spectrum, log10(FWHM/{\sigma})rms, and the virial coefficient, log10(frms,{\sigma}), and investigate how BLR properties might be related to line-profile shape using caramel models.
Keywords
Cite
@article{arxiv.2304.06764,
title = {What Does the Virial Coefficient of the \Hb Broad-Line Region Depend On?},
author = {Lizvette Villafaña and Peter R. Williams and Tommaso Treu and Brendon J. Brewer and Aaron J. Barth and Vivian U and Vardha N. Bennert and Hengxiao Guo and Misty C. Bentz and Gabriela Canalizo and Alexei V. Filippenko and Elinor Gates and Michael D. Joner and Matthew A. Malkan and Jong-Hak Woo and Bela Abolfathi and Thomas Bohn and K. Azalee Bostroem and Andrew Brandel and Thomas G. Brink and Sanyum Channa and Maren Cosens and Edward Donohue and Goni Halevi and Carol E. Hood and J. Chuck Horst and Maxime de Kouchkovsky and Benjamin Kuhn and Douglas C. Leonard and Raul Michel and Melanie Kae B. Olaes and Daeseong Park and Jordan N. Runco and Remington O. Sexton and Isaac Shivvers and Chance L. Spencer and Benjamin E. Stahl and Samantha Stegman and Jonelle L. Walsh and WeiKang Zheng},
journal= {arXiv preprint arXiv:2304.06764},
year = {2026}
}
Comments
17 pages, 10 figures