| Issue |
A&A
Volume 663, July 2022
|
|
|---|---|---|
| Article Number | L4 | |
| Number of page(s) | 5 | |
| Section | Letters to the Editor | |
| DOI | https://doi.org/10.1051/0004-6361/202244105 | |
| Published online | 08 July 2022 | |
Letter to the Editor
Constraining X-ray emission of a magnetically arrested disk by radio-loud AGNs with an extreme-ultraviolet deficit
1
Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PR China
e-mail: lisl@shao.ac.cn; gumf@shao.ac.cn
2
University of Chinese Academy of Sciences, 19A Yuquan Road, 100049 Beijing, PR China
3
School of Physics and Electronic Information, Shangrao Normal University, 401 Zhimin Road, Shangrao 334001, PR China
e-mail: zhoumh8@163.com
Received:
24
May
2022
Accepted:
28
June
2022
Aims. Active galactic nuclei (AGNs) with an extreme-ultraviolet (EUV) deficit are suggested to be powered by a magnetically arrested disk (MAD) surrounding the black hole, where the slope of EUV spectra (αEUV) is found to possess a clearly positive relationship with the jet efficiency. In this work, we investigate the properties of X-ray emission in AGNs with an EUV deficit for the first time.
Methods. We constructed a sample of 15 objects with an EUV deficit to analyze their X-ray emission. The X-ray luminosity in 13 objects was recently processed by us, while the other two sources were gathered from archival data.
Results. It is found that the average X-ray flux of AGNs with an EUV deficit are 4.5 times larger than that of radio-quiet AGNs (RQAGNs), while the slope of the relationship between the optical-UV luminosity (LUV) and the X-ray luminosity (LX) is found to be similar with that of RQAGNs. For comparison, the average X-ray flux of radio-loud AGNs (RLAGNs) without an EUV deficit is about 2–3 times larger than that of RQAGNs. A strong positive correlation between αEUV and radio loudness (RUV) is also reported. However, there is no strong relationship between LX and the radio luminosity (LR).
Conclusions. Both the excess of X-ray emission of RLAGNs with an EUV deficit and the strong αEUV − RUV relationship can be qualitatively explained with the MAD scenario, which can help one to constrain the theoretical model of MAD.
Key words: accretion, accretion disks / black hole physics / magnetohydrodynamics (MHD) / galaxies: active / X-rays: galaxies
© S.-L. Li et al. 2022
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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