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Title: A bayesian approach to estimate the size and structure of the broad-line region in active galactic nuclei using reverberation mapping data

This is the first paper in a series devoted to the systematic study of the size and structure of the broad-line region (BLR) in active galactic nuclei (AGNs) using reverberation mapping (RM) data. We employ a recently developed Bayesian approach that statistically describes the variability as a damped random walk process and delineates the BLR structure using a flexible disk geometry that can account for a variety of shapes, including disks, rings, shells, and spheres. We allow for the possibility that the line emission may respond non-linearly to the continuum, and we detrend the light curves when there is clear evidence for secular variation. We use a Markov Chain Monte Carlo implementation based on Bayesian statistics to recover the parameters and uncertainties for the BLR model. The corresponding transfer function is obtained self-consistently. We tentatively constrain the virial factor used to estimate black hole masses; more accurate determinations will have to await velocity-resolved RM data. Application of our method to RM data with Hβ monitoring for about 40 objects shows that the assumed BLR geometry can reproduce quite well the observed emission-line fluxes from the continuum light curves. We find that the Hβ BLR sizes obtained from our method aremore » on average ∼20% larger than those derived from the traditional cross-correlation method. Nevertheless, we still find a tight BLR size-luminosity relation with a slope of α = 0.55 ± 0.03 and an intrinsic scatter of ∼0.18 dex. In particular, we demonstrate that our approach yields appropriate BLR sizes for some objects (such as Mrk 142 and PG 2130+099) where traditional methods previously encountered difficulties.« less
Authors:
; ;  [1] ;  [2] ;  [3]
  1. Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049 (China)
  2. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
  3. National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011 (China)
Publication Date:
OSTI Identifier:
22348472
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 779; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; CORRELATIONS; DATA ANALYSIS; EMISSION; GALAXIES; GALAXY NUCLEI; GRAPH THEORY; LUMINOSITY; MARKOV PROCESS; MASS; MONTE CARLO METHOD; QUASARS; RANDOMNESS; TRANSFER FUNCTIONS; VARIATIONS; VELOCITY; VISIBLE RADIATION