2024/06/12 by Minjin Kim, Kim, Minjin, Suyeon Son +3
Engineering · #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Optical Systems and Laser Technology
paper · pdf · doi:10.48550/arxiv.2406.07863
openalex publication_date 2024/06/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We investigate the optical variability of low-redshift (0.15< z≤0.4) active galactic nuclei using the multi-epoch data from the Zwicky Transient Facility. We find that a damped random walk model well describes the ensemble structure function in the g band. Consistent with previous studies, more luminous active galactic nuclei tend to have a steeper structure function at a timescale less than the break timescale and smaller variability amplitude. By comparing the structure functions in the optical with the mid-infrared obtained from the Wide-field Infrared Survey Explorer, we derive the size of the dusty torus using a toy model for the geometry of the torus. The size of the torus positively correlates with the luminosity of the active nucleus, following a relation that agrees well with previous studies based on reverberation mapping. This result demonstrates that the structure function method can be used as a powerful and highly efficient tool to examine the size of the torus.