Baseline-Aware Dependence fitting for DAmping Timescales (BADDAT): A Nearly Unbiased Approach to Constraining Optical Variability Dependence on Physical Properties of Active Galactic Nuclei

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Main Authors: Xia, Ruisong, Cai, Zhen-Yi, Xue, Yongquan, Lu, Xian-Liang, Ren, Guowei, Zhou, Shuying, Sun, Mouyuan, Zhu, Shifu, Su, Zhen-Bo, Liu, Hao
Format: Preprint
Published: 2025
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author Xia, Ruisong
Cai, Zhen-Yi
Xue, Yongquan
Lu, Xian-Liang
Ren, Guowei
Zhou, Shuying
Sun, Mouyuan
Zhu, Shifu
Su, Zhen-Bo
Liu, Hao
author_facet Xia, Ruisong
Cai, Zhen-Yi
Xue, Yongquan
Lu, Xian-Liang
Ren, Guowei
Zhou, Shuying
Sun, Mouyuan
Zhu, Shifu
Su, Zhen-Bo
Liu, Hao
contents Active galactic nuclei (AGNs) exhibit stochastic optical variability, commonly characterized by a damped random walk. The damping timescale is of particular interest because it is related to fundamental properties of the central black hole, such as its mass and accretion rate. However, the systematic underestimation of damping timescales caused by limited observational baselines makes it difficult to exhaustively utilize all available data. Many previous efforts have relied on strict selection criteria to avoid biased measurements, and such criteria inevitably constrain the range of AGN physical parameter space and therefore hinder robust inference of the underlying dependencies of damping timescale on AGN properties. In contrast, we introduce a novel forward modeling approach, Baseline-Aware Dependence fitting for DAmping Timescales (BADDAT), which explicitly accounts for these biases and leverages the information contained in underestimated timescale measurements. Rather than attempting to correct individual timescale measurements, BADDAT robustly constrains the population-level dependence of damping timescale on AGN physical properties. We demonstrate its effectiveness using mock light curves and show that it successfully reconciles previous inconsistent results based on two independent AGN samples. Our BADDAT method will have broad applications in AGN variability studies during the era of time-domain astronomy.
format Preprint
id arxiv_https___arxiv_org_abs_2509_21855
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Baseline-Aware Dependence fitting for DAmping Timescales (BADDAT): A Nearly Unbiased Approach to Constraining Optical Variability Dependence on Physical Properties of Active Galactic Nuclei
Xia, Ruisong
Cai, Zhen-Yi
Xue, Yongquan
Lu, Xian-Liang
Ren, Guowei
Zhou, Shuying
Sun, Mouyuan
Zhu, Shifu
Su, Zhen-Bo
Liu, Hao
Astrophysics of Galaxies
Instrumentation and Methods for Astrophysics
Active galactic nuclei (AGNs) exhibit stochastic optical variability, commonly characterized by a damped random walk. The damping timescale is of particular interest because it is related to fundamental properties of the central black hole, such as its mass and accretion rate. However, the systematic underestimation of damping timescales caused by limited observational baselines makes it difficult to exhaustively utilize all available data. Many previous efforts have relied on strict selection criteria to avoid biased measurements, and such criteria inevitably constrain the range of AGN physical parameter space and therefore hinder robust inference of the underlying dependencies of damping timescale on AGN properties. In contrast, we introduce a novel forward modeling approach, Baseline-Aware Dependence fitting for DAmping Timescales (BADDAT), which explicitly accounts for these biases and leverages the information contained in underestimated timescale measurements. Rather than attempting to correct individual timescale measurements, BADDAT robustly constrains the population-level dependence of damping timescale on AGN physical properties. We demonstrate its effectiveness using mock light curves and show that it successfully reconciles previous inconsistent results based on two independent AGN samples. Our BADDAT method will have broad applications in AGN variability studies during the era of time-domain astronomy.
title Baseline-Aware Dependence fitting for DAmping Timescales (BADDAT): A Nearly Unbiased Approach to Constraining Optical Variability Dependence on Physical Properties of Active Galactic Nuclei
topic Astrophysics of Galaxies
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2509.21855