Probing the Optical/UV Continuum Variability of Active Galactic Nuclei with the Damped Random Walk Model
Abstract
Optical/UV continuum variability over baselines of up to 20 yr is investigated using the damped random walk (DRW) model for 1214 active galactic nuclei (AGNs) compiled from Y. Shen et al. and C. J. Burke et al. Among these, 115 AGNs with reliable DRW fitting and unbiased DRW parameters (timescale τ ₂₅₀₀ and amplitude σ ₂₅₀₀ at the rest-frame 2500 Å) are used to examine the relations between the variability and the accretion properties. We found a significant correlation of τ ₂₅₀₀ with black hole mass ( M BH ) and dimensionless accretion rate ( M ̇ ) of the form τ 2500 ∝ M BH 0.50 ± 0.07 M ̇ 0.27 ± 0.04 , while the dependence on the continuum luminosity at 5100 Å and redshift becomes insignificant after controlling for M BH . τ ₂₅₀₀ also correlates with the mass accretion rate ( M ̇ ) as τ 2500 ∝ M ̇ 0.41 ± 0.04 , which is consistent with the thermal timescale expected from the standard thin-disk model within 3 σ uncertainties; while the average value is consistent with the expectations of the model, the scatter in the relation can be due to differences in the viscosity parameter ( α ) or in disk temperature profiles. Assuming that τ ₂₅₀₀ corresponds to the accretion disk thermal timescale, the disk-emitting radius at rest-frame 2500 Å ( R ₂₅₀₀ ) is found to correlate with M BH as R 2500 ∝ M BH 0.53 ± 0.05 . Using the microlensing-based R ₂₅₀₀ – M BH relation of C. W. Morgan et al., α is statistically estimated to be 0.04 ± 0.01.
Related
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- Nuclear Millimeter Continuum Emission in Radio-Quiet Active Galactic Nuclei: an ALMA Spectral and Variability Study
- Relations between optical spectral parameters and the (far-)infrared continuum in Type~1 active galactic nuclei
- Migration Traps as Variability Attractors. I. Optical/UV Signatures of Embedded Stellar-Mass Black Holes in Active Galactic Nucleus Disks
- Migration Traps as Variability Attractors. I. Optical/UV Signatures of Embedded Stellar-mass Black Holes in Active Galactic Nucleus Disks
BibTeX
@article{ning2026probing,
title = {{Probing the Optical/UV Continuum Variability of Active Galactic Nuclei with the Damped Random Walk Model}},
author = {Xiang-Wei Ning and 翔炜 宁 and Wen-Jie Hu and 文杰 胡 and Zi-Han Yuan and 子涵 袁 and Yi Tang and 逸 唐 and Yan-Song Ma and 岩松 马 and Yu-Meng Guan and 雨蒙 官 and Le-Yi Huang and 乐奕 黄 and Wei-Hao Bian and 维豪 卞},
journal = {The Astrophysical Journal},
year = {2026},
month = nov,
doi = {10.3847/1538-4357/aeb010},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeb010},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Probing the Optical/UV Continuum Variability of Active Galactic Nuclei with the Damped Random Walk Model
AU - Xiang-Wei Ning
AU - 翔炜 宁
AU - Wen-Jie Hu
AU - 文杰 胡
AU - Zi-Han Yuan
AU - 子涵 袁
AU - Yi Tang
AU - 逸 唐
AU - Yan-Song Ma
AU - 岩松 马
AU - Yu-Meng Guan
AU - 雨蒙 官
AU - Le-Yi Huang
AU - 乐奕 黄
AU - Wei-Hao Bian
AU - 维豪 卞
PY - 2026
DA - 2026/11/05
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aeb010
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aeb010
AB - Optical/UV continuum variability over baselines of up to 20 yr is investigated using the damped random walk (DRW) model for 1214 active galactic nuclei (AGNs) compiled from Y. Shen et al. and C. J. Burke et al. Among these, 115 AGNs with reliable DRW fitting and unbiased DRW parameters (timescale τ ₂₅₀₀ and amplitude σ ₂₅₀₀ at the rest-frame 2500 Å) are used to examine the relations between the variability and the accretion properties. We found a significant correlation of τ ₂₅₀₀ with black hole mass ( M BH ) and dimensionless accretion rate ( M ̇ ) of the form τ 2500 ∝ M BH 0.50 ± 0.07 M ̇ 0.27 ± 0.04 , while the dependence on the continuum luminosity at 5100 Å and redshift becomes insignificant after controlling for M BH . τ ₂₅₀₀ also correlates with the mass accretion rate ( M ̇ ) as τ 2500 ∝ M ̇ 0.41 ± 0.04 , which is consistent with the thermal timescale expected from the standard thin-disk model within 3 σ uncertainties; while the average value is consistent with the expectations of the model, the scatter in the relation can be due to differences in the viscosity parameter ( α ) or in disk temperature profiles. Assuming that τ ₂₅₀₀ corresponds to the accretion disk thermal timescale, the disk-emitting radius at rest-frame 2500 Å ( R ₂₅₀₀ ) is found to correlate with M BH as R 2500 ∝ M BH 0.53 ± 0.05 . Using the microlensing-based R ₂₅₀₀ – M BH relation of C. W. Morgan et al., α is statistically estimated to be 0.04 ± 0.01.
SN - 1538-4357
SN - 0004-637X
ER -