NGC 3227 Blinks: An Extreme Changing-Look Event in a Seyfert Galaxy
Abstract
We report a rapid optical changing-look event in the Seyfert galaxy NGC 3227: the optical continuum faded by more than 70% and broad H-beta emission nearly disappeared within weeks, before recovering within two months. Damped random walk simulations calibrated to the source's normal variability show that such a decline is unlikely for stochastic accretion fluctuations (p = 0.002). Simultaneous Swift monitoring reveals X-ray spectral hardening, pointing to enhanced line-of-sight absorption. During the dim state, reverberation mapping yields a persistent 6-8 day lag between the continuum and broad H-beta, showing that the broad-line region continued to reverberate and placing the obscurer interior to the broad-line region. Photoionization calculations require a fully ionized, Compton-thick column with N_H ~ 1.5 x 10^24 cm^-2 to reproduce the optical continuum suppression. Together, these observations demonstrate that compact, high-column-density obscurers interior to the broad-line region can produce extreme optical changing-look behavior on week timescales.
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BibTeX
@misc{zhang20263227,
title = {{NGC 3227 Blinks: An Extreme Changing-Look Event in a Seyfert Galaxy}},
author = {Kaiwen Zhang and Michael S. Brotherton and Pu Du and Dong-Wei Bao and Bi-Xuan Zhao and Feng-na Fang and Yan-Rong Li and Chen Hu and Ming Xiao and Keith Horne and Gerard A. Kriss and Daniel Proga and Jian-Min Wang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29137},
eprint = {2610.29137},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29137},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - NGC 3227 Blinks: An Extreme Changing-Look Event in a Seyfert Galaxy
AU - Kaiwen Zhang
AU - Michael S. Brotherton
AU - Pu Du
AU - Dong-Wei Bao
AU - Bi-Xuan Zhao
AU - Feng-na Fang
AU - Yan-Rong Li
AU - Chen Hu
AU - Ming Xiao
AU - Keith Horne
AU - Gerard A. Kriss
AU - Daniel Proga
AU - Jian-Min Wang
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.29137
UR - https://arxiv.org/abs/2610.29137
AB - We report a rapid optical changing-look event in the Seyfert galaxy NGC 3227: the optical continuum faded by more than 70% and broad H-beta emission nearly disappeared within weeks, before recovering within two months. Damped random walk simulations calibrated to the source's normal variability show that such a decline is unlikely for stochastic accretion fluctuations (p = 0.002). Simultaneous Swift monitoring reveals X-ray spectral hardening, pointing to enhanced line-of-sight absorption. During the dim state, reverberation mapping yields a persistent 6-8 day lag between the continuum and broad H-beta, showing that the broad-line region continued to reverberate and placing the obscurer interior to the broad-line region. Photoionization calculations require a fully ionized, Compton-thick column with N_H ~ 1.5 x 10^24 cm^-2 to reproduce the optical continuum suppression. Together, these observations demonstrate that compact, high-column-density obscurers interior to the broad-line region can produce extreme optical changing-look behavior on week timescales.
ER -