A Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian Component

作者：Jiancheng Wu, Qingwen Wu, Chen Hu, Bing Lyu, Hua-Rui Bai, Yi-Xin Fu, Yu Zhao, Jianmin Wang, Xinwu Cao · 发表于：Astrophysical Journal · 年份：2025 · DOI：10.3847/1538-4357/ade2cc · 被引用次数：2 · 研究领域：Physics

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 Hα 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 ∼10 yr. We find that the size of the central Gaussian (full width at half-maximum, FWHM ∼ 3000 km s−1) component is consistent with the classical reverberation mapping correlation. In contrast, the asymmetric double-peaked wing (FWHM ∼ 23,000 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.