Issue |
A&A
Volume 689, September 2024
|
|
---|---|---|
Article Number | A27 | |
Number of page(s) | 7 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/202450413 | |
Published online | 30 August 2024 |
The size-luminosity relation of the AGN torus determined from the comparison between optical and mid-infrared variability
1
Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu 41566, Korea
2
Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
3
Department of Astronomy, School of Physics, Peking University, Beijing 100871, China
Received:
17
April
2024
Accepted:
10
June
2024
We investigate the optical variability of low-redshift (0.15 < z ≤ 0.4) active galactic nuclei using multi-epoch data from the Zwicky Transient Facility. We find that a damped random walk model describes well 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 a 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.
Key words: quasars: general / galaxies: Seyfert
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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