The Intrinsic Structure of Sagittarius A* at 1.3 cm and 7 mm
The Intrinsic Structure of Sagittarius A* at 1.3 cm and 7 mm
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DOI：
10.3847/1538-4357/ac4165
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发表时间：
2021-12
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通讯作者：
I. Cho;Guangyao Zhao;T. Kawashima;M. Kino;K. Akiyama;Michael D. Johnson;S. Issaoun;Kotaro Moriyama;Xiaopeng Cheng;J. Algaba;T. Jung;B. Sohn;T. Krichbaum;M. Wielgus;K. Hada;R. Lu;Yuzhu Cui;S. Sawada-Satoh;Zhiqiang Shen;Jongho Park;Wu Jiang;H. Ro;K. -H. Yi;K. Wajima;J. Lee;J. Hodgson;F. Tazaki;M. Honma;K. Niinuma;S. Trippe;T. An;Yingkang Zhang;J. Lee;Se-jin Oh;D. Byun;Sang-Sung Lee;Jae-Young Kim;J. Oh;S. Koyama;K. Asada;Xuezheng Wang;L. Cui;Y. Hagiwara;M. Nakamura;M. Takamura;T. Hirota;K. Sugiyama;N. Kawaguchi;H. Kobayashi;T. Oyama;Y. Yonekura;Jongsoo Kim;Ju-Yeon Hwang;Dong-Kyu Jung;Hyo-Ryoung Kim;Jeong-Sook Kim;C. Oh;D. Roh;J. Yeom;B. Xia;Weiye Zhong;Bin Li;Rongbin Zhao;Jinqing Wang;Qing-Hui Liu;Zhong Chen Korea Astronomy;S. S. Institute-S.;University of Electronic Science;Technology;Instituto de Astrofisica de Andalucia-CSIC-Instituto-de-Astrofisica-de-Andalucia-CSIC-1405262109;Inst. for Nucl. Research;T. U. O. Tokyo;National Space Development Agency of Japan;Kogakuin University of Technology;Engineering;Massachusetts Institute of TechnologyHaystack Observatory-Massachusetts-Institute-of-TechnologyHaystack-1720696614;Black Hole Initiative at Harvard University;Center for Computational Astrophysics;Harvard;Smithsonian;D. O. Astrophysics;Institute for Applied Mathematics;Astrophysics;P. Physics;R. University;Mizusawa Vlbi Observatory;Department of Materials Science;U. Malaya;D. Astronomy;Y. University;M. F. Radioastronomie;Department of Materials Science;The Graduate University for Advanced Studies;S. Observatory;Key Laboratory of Optical Astronomy;The Graduate University for Advanced Studies;Y. University;I. O. Astronomy;A. Sinica;D. Physics;Astronomy;Seoul National University;Sejong University;G. S. O. Sciences;Technology for Innovation;Snu Astronomy Research Center;Niigata University;Xinjiang Astronomical Observatory;Toyo University;National Institute of Technology;Hachinohe College;National Astronomical Research Institute of Thailand-National-Astronomical-Research-Institute-of-102749703;C. F. Astronomy;I. University;B. S. R. Institute;Chungbuk National University
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文献类型：
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作者：
I. Cho;Guangyao Zhao;T. Kawashima;M. Kino;K. Akiyama;Michael D. Johnson;S. Issaoun;Kotaro Moriyama;Xiaopeng Cheng;J. Algaba;T. Jung;B. Sohn;T. Krichbaum;M. Wielgus;K. Hada;R. Lu;Yuzhu Cui;S. Sawada-Satoh;Zhiqiang Shen;Jongho Park;Wu Jiang;H. Ro;K. -H. Yi;K. Wajima;J. Lee;J. Hodgson;F. Tazaki;M. Honma;K. Niinuma;S. Trippe;T. An;Yingkang Zhang;J. Lee;Se-jin Oh;D. Byun;Sang-Sung Lee;Jae-Young Kim;J. Oh;S. Koyama;K. Asada;Xuezheng Wang;L. Cui;Y. Hagiwara;M. Nakamura;M. Takamura;T. Hirota;K. Sugiyama;N. Kawaguchi;H. Kobayashi;T. Oyama;Y. Yonekura;Jongsoo Kim;Ju-Yeon Hwang;Dong-Kyu Jung;Hyo-Ryoung Kim;Jeong-Sook Kim;C. Oh;D. Roh;J. Yeom;B. Xia;Weiye Zhong;Bin Li;Rongbin Zhao;Jinqing Wang;Qing-Hui Liu;Zhong Chen Korea Astronomy;S. S. Institute-S.;University of Electronic Science;Technology;Instituto de Astrofisica de Andalucia-CSIC-Instituto-de-Astrofisica-de-Andalucia-CSIC-1405262109;Inst. for Nucl. Research;T. U. O. Tokyo;National Space Development Agency of Japan;Kogakuin University of Technology;Engineering;Massachusetts Institute of TechnologyHaystack Observatory-Massachusetts-Institute-of-TechnologyHaystack-1720696614;Black Hole Initiative at Harvard University;Center for Computational Astrophysics;Harvard;Smithsonian;D. O. Astrophysics;Institute for Applied Mathematics;Astrophysics;P. Physics;R. University;Mizusawa Vlbi Observatory;Department of Materials Science;U. Malaya;D. Astronomy;Y. University;M. F. Radioastronomie;Department of Materials Science;The Graduate University for Advanced Studies;S. Observatory;Key Laboratory of Optical Astronomy;The Graduate University for Advanced Studies;Y. University;I. O. Astronomy;A. Sinica;D. Physics;Astronomy;Seoul National University;Sejong University;G. S. O. Sciences;Technology for Innovation;Snu Astronomy Research Center;Niigata University;Xinjiang Astronomical Observatory;Toyo University;National Institute of Technology;Hachinohe College;National Astronomical Research Institute of Thailand-National-Astronomical-Research-Institute-of-102749703;C. F. Astronomy;I. University;B. S. R. Institute;Chungbuk National University
人马座A*（Sgr A*），银河系中心超大质量黑洞（SMBH），是用甚长基线干涉测量（VLBI）解析SMBH最内层区域的最佳目标之一。在这项研究中，我们利用东亚VLBI网络对Sgr A* 进行了1.349 cm（22.223 GHz）和6.950 mm（43.135 GHz）的观测，作为事件视界望远镜（EHT）多波长活动的一部分2017年4月。为了减轻散射效应，应用了Psaltis等人（2018）的物理激励散射核模型和约翰逊等人（2018）的散射参数。因此，一个单一的，对称的高斯模型很好地描述了在两个波长的Sgr A* 的固有结构。根据闭合振幅，在1.349 cm和6.95 mm处，长轴尺寸分别为<$704 ± 102 μas（轴比<$1.19 − 0.19 + 0.24）和<$300 ± 25 μas（轴比<$1.28 ± 0.2）。结合Issaoun等人（2019）在3.5 mm（86 GHz）处的准同时观测，我们发现固有尺寸与观测波长呈幂律关系，指数为1.2 ± 0.2。我们的研究结果还提供了估计的大小和紧凑的通量密度在1.3毫米，这可以纳入分析的EHT观测。在射电辐射的起源方面，我们比较了内禀结构与吸积流的情况，特别是基于开普勒壳模型的辐射无效吸积流。有了这个，我们表明，一个非热电子人口是必要的，以重现源的大小。
Sagittarius A* (Sgr A*), the Galactic Center supermassive black hole (SMBH), is one of the best targets in which to resolve the innermost region of an SMBH with very long baseline interferometry (VLBI). In this study, we have carried out observations toward Sgr A* at 1.349 cm (22.223 GHz) and 6.950 mm (43.135 GHz) with the East Asian VLBI Network, as a part of the multiwavelength campaign of the Event Horizon Telescope (EHT) in 2017 April. To mitigate scattering effects, the physically motivated scattering kernel model from Psaltis et al. (2018) and the scattering parameters from Johnson et al. (2018) have been applied. As a result, a single, symmetric Gaussian model well describes the intrinsic structure of Sgr A* at both wavelengths. From closure amplitudes, the major-axis sizes are ∼704 ± 102 μas (axial ratio ∼ 1.19 − 0.19 + 0.24 ) and ∼300 ± 25 μas (axial ratio ∼1.28 ± 0.2) at 1.349 cm and 6.95 mm, respectively. Together with a quasi-simultaneous observation at 3.5 mm (86 GHz) by Issaoun et al. (2019), we show that the intrinsic size scales with observing wavelength as a power law, with an index ∼1.2 ± 0.2. Our results also provide estimates of the size and compact flux density at 1.3 mm, which can be incorporated into the analysis of the EHT observations. In terms of the origin of radio emission, we have compared the intrinsic structures with the accretion flow scenario, especially the radiatively inefficient accretion flow based on the Keplerian shell model. With this, we show that a nonthermal electron population is necessary to reproduce the source sizes.