Multifrequency Very Long Baseline Interferometry Study of Emission and Absorption in the Two-sided Jets of NGC 3998
文献类型：期刊论文
| 作者 | Yan, Xi2; Cui, Lang1,2,3 ; Ho, Luis C.4,5
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| 刊名 | ASTROPHYSICAL JOURNAL
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| 出版日期 | 2025-04-20 |
| 卷号 | 983期号:2页码:169 |
| ISSN号 | 0004-637X |
| DOI | 10.3847/1538-4357/adc003 |
| 产权排序 | 1 |
| 英文摘要 | We present the multifrequency, multi-epoch very long baseline interferometry (VLBI) study of the two-sided jets in the low-luminosity active galactic nucleus NGC 3998, where physical properties of the jets on parsec scales remain poorly understood. Using Very Long Baseline Array data observed at 1.4, 1.7, 2.3, and 5 GHz, we detect symmetric twin jets aligned along the north-south direction, with a total extent of similar to 5.3 pc. Notably, the position angle of the parsec-scale jets differs by 26 degrees-30 degrees from that of the kiloparsec-scale jets, suggesting the possibility of jet precession. Based on the frequency-dependent core shift and north/south jet brightness ratio, we identify the northern jet as the approaching jet and the southern jet as the counterjet. Measurements of the radial intensity profile on both sides indicate a change in the counterjet emission from rapid fading to a slower decline at 1.4, 1.7, and 2.3 GHz. Spectral analysis shows that the approaching jet exhibits an optically thin spectrum, while the counterjet is dominated by an optically thick, inverted spectrum. These findings tentatively suggest free-free absorption in NGC 3998, which should be verified in future studies. Finally, our observations also reveal a flat-spectrum VLBI core, showing significant radio variability that is likely linked to a jet ejection event. |
| WOS关键词 | ACTIVE GALACTIC NUCLEI ; DENSE-PLASMA TORUS ; PARSEC-SCALE JET ; ACCRETION DISK ; X-RAY ; RADIO-SOURCES ; VLBI OBSERVATIONS ; CORE-SHIFT ; BLACK-HOLE ; 3C 84 |
| 资助项目 | CAS divided by West Light Foundation, Chinese Academy of Sciences (West Light Foundation of CAS)https://doi.org/10.13039/501100013494[2021-XBQNXZ-005] ; CAS Light of West China Program[2022SKA0120102] ; CAS Light of West China Program[2025] ; National SKA Program of China ; Xinjiang Uygur Autonomous Region[2023TSYCCX0099] ; Tianshan Talent Training Program ; Xinjiang Tianchi Talent Program[2022YFF0503401] ; National Key R&D Program of China[11991052] ; National Key R&D Program of China[12233001] ; National Science Foundation of China[CMS-CSST-2021-A04] ; National Science Foundation of China[CMS-CSST-2021-A06] ; China Manned Space Project[XJYWZ2303] ; Urumqi Nanshan Astronomy and Deep Space Exploration Observation and Research Station of Xinjiang |
| WOS研究方向 | Astronomy & Astrophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:001469230500001 |
| 出版者 | IOP Publishing Ltd |
| 资助机构 | CAS divided by West Light Foundation, Chinese Academy of Sciences (West Light Foundation of CAS)https://doi.org/10.13039/501100013494 ; CAS Light of West China Program ; National SKA Program of China ; Xinjiang Uygur Autonomous Region ; Tianshan Talent Training Program ; Xinjiang Tianchi Talent Program ; National Key R&D Program of China ; National Science Foundation of China ; China Manned Space Project ; Urumqi Nanshan Astronomy and Deep Space Exploration Observation and Research Station of Xinjiang |
| 源URL | [http://ir.xao.ac.cn/handle/45760611-7/7693]  |
| 专题 | 星系宇宙学研究团组 |
| 通讯作者 | Cui, Lang |
| 作者单位 | 1.Chinese Acad Sci, Key Lab Radio Astron & Technol, A20 Datun Rd, Beijing 100101, Peoples R China 2.Chinese Acad Sci, Xinjiang Astron Observ, 150 Sci 1 St, Urumqi 830011, Xinjiang, Peoples R China 3.Xinjiang Key Lab Radio Astrophys, 150 Sci 1 St, Urumqi 830011, Peoples R China 4.Peking Univ, Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China 5.Peking Univ, Sch Phys, Dept Astron, Beijing 100871, Peoples R China |
| 推荐引用方式 GB/T 7714 | Yan, Xi,Cui, Lang,Ho, Luis C.. Multifrequency Very Long Baseline Interferometry Study of Emission and Absorption in the Two-sided Jets of NGC 3998[J]. ASTROPHYSICAL JOURNAL,2025,983(2):169. |
| APA | Yan, Xi,Cui, Lang,&Ho, Luis C..(2025).Multifrequency Very Long Baseline Interferometry Study of Emission and Absorption in the Two-sided Jets of NGC 3998.ASTROPHYSICAL JOURNAL,983(2),169. |
| MLA | Yan, Xi,et al."Multifrequency Very Long Baseline Interferometry Study of Emission and Absorption in the Two-sided Jets of NGC 3998".ASTROPHYSICAL JOURNAL 983.2(2025):169. |
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