2025-07-10 中国科学院（CAS）
Figure 1: fitting of optical light curves using the damped random walk model within Gaussian process, with an evaluation of the fitting performance. (Image by Dr. XIONG Dingrong)
中国科学院雲南天文台のXIONG Dingrong博士らの研究チームは、ジェットを持つ活動銀河核（jetted AGN）の変動メカニズムに新たな知見を加えた。ZTFによる長期の光学観測データを用い、DRW（減衰ランダムウォーク）モデルとガウス過程を組み合わせて解析。従来にない規模のγ線放射型AGNを対象に、ジェット出力（γ線光度）を加味した非パラメトリック回帰法を用いた。その結果、従来の単一DRWモデルでは多様な変動特性を説明できず、ブラックホール質量やジェット出力との新たな相関が確認された。高降着率型では降着円盤とジェット内衝撃波が主因で、低降着率型では電子の脱出時間に対応することが示された。これはAGN変動理解の前進につながる成果である
。＜関連情報＞
- https://english.cas.cn/newsroom/research_news/phys/202507/t20250714_1047318.shtml
- https://iopscience.iop.org/article/10.3847/1538-4365/add481
ジェット活動銀河核における特徴的な光学変動タイムスケール： 大規模ガンマ線放出サンプル A Characteristic Optical Variability Timescale in Jetted Active Galactic Nuclei: A Large Gamma-Ray Emission Sample
Dingrong Xiong, Mouyuan Sun, Jun-Xian Wang, Junhui Fan, Yongquan Xue, Minfeng Gu, Liang Chen, Yongyun Chen, Nan Ding, Fei Guo,…
The Astrophysical Journal Supplement Series
DOI:10.3847/1538-4365/add481
The Astrophysical Journal Supplement Series
DOI:10.3847/1538-4365/add481
Abstract
The variability mechanisms from jetted active galactic nuclei (AGNs) are still under debate. Here, the damped random walk (DRW) model, implemented through Gaussian processes (GPs), is used to fit the Zwicky Transient Facility long-term optical light curves of 1684 gamma-ray emission jetted AGNs. This analysis yields one of the largest samples with characteristic optical variability timescales for jetted AGNs. A single DRW model from GPs can fit the optical light curve of most jetted AGNs well/potentially well, while there are still some jetted AGNs whose light curve cannot be fitted well by a single DRW model. After the jet power, proxied by gamma-ray luminosity, is introduced as a new parameter, new relationships among intrinsic variability time scales, black hole mass, and jet power are discovered for efficient accretion AGNs ( with scatter of approximately 0.09 dex) and for inefficient accretion AGNs ( with scatter of approximately 0.14 dex), respectively. Our results support that the optical variability of jetted AGNs with efficient accretion may originate within the standard accretion disk at UV-emitting radii similar to nonjetted AGNs, and is directly related to the acceleration of shock in the jet and then enhanced through the beaming effect in beamed AGNs. For the jetted AGNs with inefficient accretion, the intrinsic timescale is consistent with the escape timescale of electrons.
