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Peer-reviewedCC BY 4.0Monthly Notices of the Royal Astronomical Society

Constrain the size of broad-line region in NGC 1068 using submillimetre excess

  • Qi Guo1
  • Junzhi Wang1
  • Lingrui Lin2,3,4
  • Yuqiang Li5
  • Zhi-yu Zhang2,3
  • Fengyao Zhu6
6 affiliations
  1. 1Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University , Nanning 530004 ,
  2. 2School of Astronomy and Space Science, Nanjing University , Nanjing 210093 ,
  3. 3Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University, Ministry of Education , Nanjing 210023 ,
  4. 4INAF–Arcetri Astrophysical Observatory , Large E. Fermi 5, I-50125 Florence ,
  5. 5Korea Astronomy and Space Science Institute , No. 776, Daedeok-daero, Yuseong-gu, Daejeong 34055 ,
  6. 6Research Center for Computational Earth and Space Science, Zhejiang Laboratory , Hangzhou 311100 ,
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Abstract

Constraining the size of broad-line region (BLR) close to the accretion disc in active galactic nuclei (AGNs) is key to understand the central engine and evolution of AGNs. We propose a new method to constrain the BLR size, based on millimetre to submillimetre spectral energy distribution (SED), from which a submillimetre excess may be found. Such excess can be used to determine the solid angle of the free–free emission region from BLR, as a region with high electron density and optically thick at submillimetre wavelength for free–free continuum. Millimetre to submillimetre SED analysis towards the central source S1 in a nearby type II AGN NGC 1068 was done, which gave an upper limit on the solid angle of BLR region as (4.94 ± 0.61)× 10−6 arcsec2, corresponding to a radius no more than 0.085 pc. Such a constraint on the BLR size is important for estimating the masses of central supermassive black holes in AGNs.

Versions

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Cite

BibTeXRIS
BibTeX
@article{guo2026constrain,
  title = {{Constrain the size of broad-line region in NGC 1068 using submillimetre excess}},
  author = {Qi Guo and Junzhi Wang and Lingrui Lin and Yuqiang Li and Zhi-yu Zhang and Fengyao Zhu},
  journal = {Monthly Notices of the Royal Astronomical Society},
  year = {2026},
  month = oct,
  doi = {10.1093/mnras/stag1946},
  url = {https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1946/8914587},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Constrain the size of broad-line region in NGC 1068 using submillimetre excess
AU  - Qi Guo
AU  - Junzhi Wang
AU  - Lingrui Lin
AU  - Yuqiang Li
AU  - Zhi-yu Zhang
AU  - Fengyao Zhu
PY  - 2026
DA  - 2026/10/13
JO  - Monthly Notices of the Royal Astronomical Society
DO  - 10.1093/mnras/stag1946
UR  - https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1946/8914587
AB  - Constraining the size of broad-line region (BLR) close to the accretion disc in active galactic nuclei (AGNs) is key to understand the central engine and evolution of AGNs. We propose a new method to constrain the BLR size, based on millimetre to submillimetre spectral energy distribution (SED), from which a submillimetre excess may be found. Such excess can be used to determine the solid angle of the free–free emission region from BLR, as a region with high electron density and optically thick at submillimetre wavelength for free–free continuum. Millimetre to submillimetre SED analysis towards the central source S1 in a nearby type II AGN NGC 1068 was done, which gave an upper limit on the solid angle of BLR region as (4.94 ± 0.61)× 10^−6 arcsec^2, corresponding to a radius no more than 0.085 pc. Such a constraint on the BLR size is important for estimating the masses of central supermassive black holes in AGNs.
SN  - 0035-8711
SN  - 1365-2966
ER  -