Interband Lag Variability in Active Galactic Nuclei across ZTF Data from Multiple Years

Fuente: arXiv
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Auteurs principaux: Su, Zhen-Bo, Cai, Zhen-Yi, Guo, Hengxiao, Sun, Mouyuan, Wang, Jun-Xian
Format: Preprint
Publié: 2025
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author Su, Zhen-Bo
Cai, Zhen-Yi
Guo, Hengxiao
Sun, Mouyuan
Wang, Jun-Xian
author_facet Su, Zhen-Bo
Cai, Zhen-Yi
Guo, Hengxiao
Sun, Mouyuan
Wang, Jun-Xian
contents Interband lags in the optical continua of active galactic nuclei (AGN) have been observed over years of monitoring, yet their physical origins remain unclear. While variable interband lags have been found in a few individual AGN potentially, the temporal behavior of interband lags of an AGN sample has not been explored systematically. Here, we analyze the interband lags of 94 bright AGN at $z<0.8$, using both seasonal one-year and full six-year $gri$-band light curves from Zwicky Transient Facility Data Release 22. We find that more than half of 94 AGN show significant seasonal variations in the interband lags. Besides, the short-term lags, derived by averaging lags inferred from multiple seasonal light curves, are consistently smaller than the long-term lags, which are inferred from the full six-year light curves. This supports recent theoretical simulations where the lag measurement is sensitive to the baseline of light curve and the lag variation could be simply attributed to the inherent randomness of AGN variability. Our findings suggest that the interband lags of AGN are more complex and stochastic than commonly thought, and highlight the importance of high-precision time-domain surveys in uncovering the properties of AGN variability as well as the associated accretion physics.
format Preprint
id arxiv_https___arxiv_org_abs_2507_04359
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Interband Lag Variability in Active Galactic Nuclei across ZTF Data from Multiple Years
Su, Zhen-Bo
Cai, Zhen-Yi
Guo, Hengxiao
Sun, Mouyuan
Wang, Jun-Xian
Astrophysics of Galaxies
Interband lags in the optical continua of active galactic nuclei (AGN) have been observed over years of monitoring, yet their physical origins remain unclear. While variable interband lags have been found in a few individual AGN potentially, the temporal behavior of interband lags of an AGN sample has not been explored systematically. Here, we analyze the interband lags of 94 bright AGN at $z<0.8$, using both seasonal one-year and full six-year $gri$-band light curves from Zwicky Transient Facility Data Release 22. We find that more than half of 94 AGN show significant seasonal variations in the interband lags. Besides, the short-term lags, derived by averaging lags inferred from multiple seasonal light curves, are consistently smaller than the long-term lags, which are inferred from the full six-year light curves. This supports recent theoretical simulations where the lag measurement is sensitive to the baseline of light curve and the lag variation could be simply attributed to the inherent randomness of AGN variability. Our findings suggest that the interband lags of AGN are more complex and stochastic than commonly thought, and highlight the importance of high-precision time-domain surveys in uncovering the properties of AGN variability as well as the associated accretion physics.
title Interband Lag Variability in Active Galactic Nuclei across ZTF Data from Multiple Years
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2507.04359