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Main Authors: Wu, Jiancheng, Wu, Qingwen, Hu, Chen, Lyu, Bing, Bai, Hua-Rui, Fu, Yi-Xin, Zhao, Yu, Wang, Jian-Min, Cao, Xinwu
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2506.07161
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author Wu, Jiancheng
Wu, Qingwen
Hu, Chen
Lyu, Bing
Bai, Hua-Rui
Fu, Yi-Xin
Zhao, Yu
Wang, Jian-Min
Cao, Xinwu
author_facet Wu, Jiancheng
Wu, Qingwen
Hu, Chen
Lyu, Bing
Bai, Hua-Rui
Fu, Yi-Xin
Zhao, Yu
Wang, Jian-Min
Cao, Xinwu
contents The profiles of broad emission lines in active galactic nuclei (AGNs) provide critical insights into the geometry and kinematics of the broad-line region (BLR), which in turn influence the uncertainties in estimating the masses of central supermassive black holes. In this study, we report the discovery of a low-luminosity AGN, SDSS J1609+4902, in which the H$α$ line exhibits two distinct BLR components: a Gaussian component and an extremely broad double-peaked component. Follow-up observations conducted at the Lijiang Observatory in 2025 reveal that the line profile remains roughly unchanged, suggesting that this BLR structure may remain stable over a timescale of $\sim$10 years. We find that the size of the central Gaussian (Full Width at Half Maximum, FWHM$\sim 3000\,{\rm km\, s^{-1}}$) component is consistent with the classical reverberation mapping correlation. In contrast, the asymmetric double-peaked wing (FWHM$\sim 23,000\,{\rm km\, s^{-1}}$) likely originates from a disk-like BLR with an inner radius of approximately 70 gravitational radii. These results provide new constraints on the structure and dynamics of BLRs in AGNs and highlight the potential for long-term stability in such systems.
format Preprint
id arxiv_https___arxiv_org_abs_2506_07161
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Composite Broad-Line Region in SDSS J1609+4902: a Double-Peaked Disk component and a Gaussian Component
Wu, Jiancheng
Wu, Qingwen
Hu, Chen
Lyu, Bing
Bai, Hua-Rui
Fu, Yi-Xin
Zhao, Yu
Wang, Jian-Min
Cao, Xinwu
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
The profiles of broad emission lines in active galactic nuclei (AGNs) provide critical insights into the geometry and kinematics of the broad-line region (BLR), which in turn influence the uncertainties in estimating the masses of central supermassive black holes. In this study, we report the discovery of a low-luminosity AGN, SDSS J1609+4902, in which the H$α$ line exhibits two distinct BLR components: a Gaussian component and an extremely broad double-peaked component. Follow-up observations conducted at the Lijiang Observatory in 2025 reveal that the line profile remains roughly unchanged, suggesting that this BLR structure may remain stable over a timescale of $\sim$10 years. We find that the size of the central Gaussian (Full Width at Half Maximum, FWHM$\sim 3000\,{\rm km\, s^{-1}}$) component is consistent with the classical reverberation mapping correlation. In contrast, the asymmetric double-peaked wing (FWHM$\sim 23,000\,{\rm km\, s^{-1}}$) likely originates from a disk-like BLR with an inner radius of approximately 70 gravitational radii. These results provide new constraints on the structure and dynamics of BLRs in AGNs and highlight the potential for long-term stability in such systems.
title A Composite Broad-Line Region in SDSS J1609+4902: a Double-Peaked Disk component and a Gaussian Component
topic Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2506.07161