Instability of Circumnuclear Gas Supply as an Origin of the “Changing-look” Phenomenon of Supermassive Black Holes

作者：Jing Wang, Dawei Xu, Xinwu Cao, C. D. Gao, Conghua Xie, Jian‐Yan Wei · 发表于：The Astrophysical Journal · 年份：2024 · DOI：10.3847/1538-4357/ad4d89 · 被引用次数：22 · 研究领域：Galaxies: Formation, Evolution, Phenomena、Astrophysical Phenomena and Observations、Astrophysics and Star Formation Studies

Abstract The origin of the “changing-look” (CL) phenomenon in supermassive black holes (SMBHs) remains an open issue. This study aims to shed light on this phenomenon by focusing on a sample that encompasses all known repeating CL active galactic nuclei (AGNs). Through the identification of a characteristic timescale for the CL phenomenon, it was observed that larger SMBHs possess shorter characteristic timescales, while smaller SMBHs exhibit longer timescales. These findings reveal a significant contrast to the traditional AGN variability that has been adequately explained by the AGN’s disk instability model. This stark discrepancy highlights a distinct origin of the CL phenomenon, distinguishing it from traditional AGN variability. By properly predicting the characteristic timescale and its dependence on SMBH mass, we propose that the CL phenomenon is likely a result of a variation in accretion rate caused by a sudden change in the supply of circumnuclear gas during the transition between active and passive SMBH fueling stages.