Shuangjing Xu Richard Dodson
,1, 2 Hiroshi Imai  ,3, 4, 5 Youngjoo Yun,1 Bo Zhang,2 Mar ́ıa J. Rioja  ,6, 7, 8 ,6 Se-Hyung Cho,9 Jaeheon Kim  ,1 Lang Cui  ,10 Andrey M. Sobolev  ,11 ,12, 13 Dong-Jin Kim,14, 15 Kei Amada,3 Jun-ichi Nakashima,16 Gabor Orosz,17
James O. Chibueze
Miyako Oyadomari,3 Sejin Oh,1 Yoshinori Yonekura  ,18 Yan Sun,2, 19 Xiaofeng Mai,2, 19 Jingdong Zhang,2, 19
Shiming Wen,2 and Taehyun Jung1
Affiliation:
1Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of Korea 2Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China 3Graduate School of Science and Engineering, Kagoshima University,
1-21-35 Korimoto, Kagoshima 890-0065, Japan
4Amanogawa Galaxy Astronomy Research Center, Graduate School of Science and Engineering, Kagoshima University,
1-21-35 Korimoto, Kagoshima 890-0065, Japan
5Center for General Education, Institute for Comprehensive Education, Kagoshima University,
1-21-30 Korimoto, Kagoshima 890-0065, Japan
6ICRAR, M468, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia, 6009, Australia 7CSIRO Astronomy and Space Science, PO Box 1130, Bentley WA 6102, Australia
8Observatorio Astrono ́mico Nacional (IGN), Alfonso XII, 3 y 5, 28014 Madrid, Spain
9Astronomy program, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea/Korea
Astronomy and Space Science Institute, Yuseonggu, Daejeon 34055, Republic of Korea
10Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 150 Science 1-Street, Urumqi 830011, China 11Ural Federal University, 19 Mira Street, 620002 Ekaterinburg, Russia
12Centre for Space Research, North-West University, Potchefstroom 2520, South Africa 13Department of Physics and Astronomy, Faculty of Physical Sciences,
University of Nigeria, Carver Building, 1 University Road, Nsukka, Nigeria
14Massachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USA 15Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
16School of Physics and Astronomy, Sun Yat-sen University, 2 Daxue Road, Tangjia, Zhuhai, Guangdong Province, China 17Joint Institute for VLBI ERIC, Oude Hoogeveensedijk 4, 7991PD Dwingeloo, Netherlands
18Center for Astronomy, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
19University of Chinese Academy of Sciences, No.19 (A) Yuquan Rd. Shijingshan, Beijing, 100049, China
Abstract:
We report VLBI monitoring observations of the 22 GHz water (H2O) masers around the Mira variable BX Cam, which were carried out as a part of the EAVN Synthesis of Stellar Maser Animations (ESTEMA) project. Data of 37 epochs in total were obtained from 2018 May to 2021 June with a time interval of 3–4 weeks, spanning approximately three stellar pulsation periods (P =∼440d). In particular, the dual-beam system equipped on the VERA stations was used to measure the kinematics and parallaxes of the H2O maser features. The measured parallax, π = 1.79 ± 0.08 mas, is consistent with Gaia EDR3 and previously measured VLBI parallaxes within a 1-σ error level. The position of the central star was estimated, based on both the Gaia EDR3 data and the center position of the ring-like 43GHz silicon-monoxide (SiO) maser distribution imaged with the KVN. The three- dimensional H2O maser kinematics indicates that the circumstellar envelope is expanding at a velocity of 13 ± 4 km s−1, while there are asymmetries in both the spatial and velocity distributions of the maser features. Furthermore, the H2O maser animation achieved by our dense monitoring program manifests the propagation of shock waves in the circumstellar envelope of BX Cam.
Publications of The Korean Astronomical Society(천문학논총), Volume 37, issue 1, 1-11
Authors:
Whee Yeon Cheong 1, Sang-Hyun Kim 1, Sang-Sung Lee 1, Do-Young Byun 1, Taehyun Jung 2
Affiliation:
1 University of Science and Technology,Korea Astronomy and Space Science Institute), 2 Korea Astronomy and Space Science Institute)
Abstract:
During the course of analysing both single-dish and very long baseline interferometry (VLBI) data obtained from the Korean VLBI Network (KVN), we found a systematic offset between flux density measurements from different antennas. We were able to attribute a majority of the systematic offsets to changes in the ''a priori'' antenna gains, which were found to have varied up to 10 percent at 22 GHz and up to 30 percent at 43 GHz. Using historical calibrator observations, we present a revised set of gains that may be applied to KVN data taken from 2015 August to 2019 January. Application of the revised gains to the KVN results in a consistency of correlated flux density measurements between the three baselines of approximately ？ve percent. We found that images from the recalibrated data typically have a 50 percent higher dynamic range, with some cases showing an increase of dynamic range of up to a factor of three.
1 School of Physics and Astronomy, Sun Yat-sen University, Guangzhou 510275, People’s Republic Of China; tanbxuan@mail.sysu.edu.cn, yanglli5@mail.sysu.edu.cn, cuiyd@mail.sysu.edu.cn
2 Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of Korea; xcheng0808@gmail.com
3 Laboratory for Space Research, The University of Hong Kong, Hong Kong
4 Shanghai Astronomical Observatory, Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Shanghai 200030, Peopleʼs Republic of China 5 Department of Astronomy and Space Science, University of Science and Technology, 217 Gajeong-ro, Daejeon, Republic of Korea
6 National Astronomical Research Institute of Thailand (Public Organization), 260 Moo 4, T. Donkaew, A. Maerim, Chiang Mai, 50180, Thailand
7 Yunnan Observatories, Chinese Academy of Sciences, 650216 Kunming, Yunnan, Peopleʼs Republic of China
8 University of Chinese Academy of Sciences, 19A Yuquanlu, Beijing 100049, Peopleʼs Republic of China
Abstract:
Fermi J1544-0649 is a transient GeV source first detected during its GeV flares in 2017. Multiwavelength observations during the flaring time demonstrate variability and spectral energy distributions that are typical of a blazar. Other than the flare time, Fermi J1544-0649 is quiet in the GeV band and has looked rather like a quiet galaxy (2MASX J15441967-0649156) for a decade. Together with the broad absorption-lines-like feature we further explore the "misaligned blazar scenario." We analyzed the Very Long Baseline Array (VLBA) and East Asian VLBI Network (EAVN) data from 2018 to 2020 and discovered the four jet components from Fermi J1544-0649. We found a viewing angle around 3fdg7 to 7fdg4. The lower limit of the viewing angle indicates a blazar with an extreme low duty cycle of gamma-ray emission; the upper limit of it supports the "misaligned blazar scenario." Follow-up multiwavelength observations after 2018 show Fermi J1544-0649 remains quiet in GeV, X-ray, and optical bands. A multimessenger search of neutrinos is also performed, and an excess of 3.1σ significance is found for this source.
THE ASTROPHYSICAL JOURNAL, Volume 932, 1 pp. (2022)
Authors:
Guang-Yao Zhao1 Ilje Cho1
Silke Britzen2
Achamveedu Gopakumar11, Sara Issaoun8,13,34 , Michael Janssen2 , Svetlana Jorstad14,15 , Jae-Young Kim16,17,2
, José L. Gómez1 , Antonio Fuentes1 , Thomas P. Krichbaum2 , Efthalia Traianou1 , Rocco Lico1,3 , , Eduardo Ros2 , S. Komossa2 , Kazunori Akiyama4,5,6 , Keiichi Asada7 , Lindy Blackburn6,8 ,
, Gabriele Bruni9 , Geoffrey B. Crew4 , Rohan Dahale1,10 , Lankeswar Dey11 , Roman Gold12
, ,
Jun Yi Koay7 , Yuri Y. Kovalev18,19,2 , Shoko Koyama20,7 , Andrei P. Lobanov2 , Laurent Loinard21,22
Ru-Sen Lu23,24,2 , Sera Markoff25,26 , Alan P. Marscher14 , Iván Martí-Vidal27,28 , Yosuke Mizuno29,30,31
Jongho Park7,35 , Tuomas Savolainen32,33,2 , and Teresa Toscano1
Affiliation:
1 Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, Spain; gyzhao@iaa.es
, ,
2 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
3 INAF-Istituto di Radioastronomia, Via P. Gobetti 101, I-40129 Bologna, Italy
4 Massachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USA
5 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
6 Black Hole Initiative at Harvard University, 20 Garden Street, Cambridge, MA 02138, USA
7 Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, R.O.C.
8 Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
9 INAF—Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, I-00133 Roma, Italy
10 Indian Institute of Science Education and Research Kolkata, Mohanpur, Nadia, West Bengal 741246, India
11 Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai 400005, India
12 CP3-Origins, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
13 Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
14 Institute for Astrophysical Research, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA
15 Astronomical Institute, St. Petersburg University, Universitetskij pr., 28, Petrodvorets,198504 St.Petersburg, Russia
16 Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu 702-701, Republic of Korea
17 Korea Astronomy and Space Science Institute, Daedeok-daero 776, Yuseong-gu, Daejeon 34055, Republic of Korea
18 Lebedev Physical Institute of the Russian Academy of Sciences, Leninsky prospekt 53, 119991 Moscow, Russia
19 Moscow Institute of Physics and Technology, Institutsky per. 9, Dolgoprudny, Moscow region, 141700, Russia
20 Niigata University, 8050 Ikarashi-nino-cho, Nishi-ku, Niigata 950-2181, Japan
21 Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Morelia 58089, México
22 Instituto de Astronomía, Universidad Nacional Autónoma de México, CdMx 04510, México
23 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, Peopleʼs Republic of China
24 Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008, Peopleʼs Republic of China
25 Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
26 Gravitation and Astroparticle Physics Amsterdam (GRAPPA) Institute, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands 27 Departament d’Astronomia i Astrofísica, Universitat de València, C. Dr. Moliner 50, E-46100 Burjassot, València, Spain
28 Observatori Astronòmic, Universitat de València, C. Catedrático José Beltrán 2, E-46980 Paterna, València, Spain
29 Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shengrong Road 520, Shanghai, 201210, Peopleʼs Republic of China
30 School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, Peopleʼs Republic of China
31 Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, D-60438 Frankfurt am Main, Germany
32 Aalto University Department of Electronics and Nanoengineering, PL 15500, FI-00076 Aalto, Finland
33 Aalto University Metsähovi Radio Observatory, Metsähovintie 114, FI-02540 Kylmälä, Finland
Abstract:
We present the first very long baseline interferometric (VLBI) observations of the blazar OJ 287 carried out jointly with the Global Millimeter VLBI Array (GMVA) and the phased Atacama Large Millimeter/submillimeter Array (ALMA) at 3.5 mm on 2017 April 2. The participation of phased ALMA has not only improved the GMVA north– south resolution by a factor of ∼3, but has also enabled fringe detections with signal-to-noise ratios up to 300 at baselines longer than 2 Gλ. The high sensitivity has motivated us to image the data with newly developed regularized maximum likelihood imaging methods, revealing the innermost jet structure with unprecedentedly high angular resolution. Our images reveal a compact and twisted jet extending along the northwest direction, with two bends within the inner 200 μas, resembling a precessing jet in projection. The component at the southeastern end shows a compact morphology and high brightness temperature, and is identified as the VLBI core. An extended jet feature that lies at ∼200 μas northwest of the core shows a conical shape, in both total and linearly polarized intensity, and a bimodal distribution of the linear polarization electric vector position angle. We discuss the nature of this feature by comparing our observations with models and simulations of oblique and recollimation shocks with various magnetic field configurations. Our high-fidelity images also enabled us to search for possible jet features from the secondary supermassive black hole (SMBH) and test the SMBH binary hypothesis proposed for this source.
We present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A*), collected during the 2017 April 5-11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account for Sgr A*'s flux variability. The majority of the 1.3 mm emission arises from horizon scales, where intrinsic structural source variability is detected on timescales of minutes to hours. The effects of interstellar scattering on the image and its variability are found to be subdominant to intrinsic source structure. The calibrated visibility amplitudes, particularly the locations of the visibility minima, are broadly consistent with a blurred ring with a diameter of ~50 μas, as determined in later works in this series. Contemporaneous multiwavelength monitoring of Sgr A* was performed at 22, 43, and 86 GHz and at near-infrared and X-ray wavelengths. Several X-ray flares from Sgr A* are detected by Chandra, one at low significance jointly with Swift on 2017 April 7 and the other at higher significance jointly with NuSTAR on 2017 April 11. The brighter April 11 flare is not observed simultaneously by the EHT but is followed by a significant increase in millimeter flux variability immediately after the X-ray outburst, indicating a likely connection in the emission physics near the event horizon. We compare Sgr A*'s broadband flux during the EHT campaign to its historical spectral energy distribution and find that both the quiescent emission and flare emission are consistent with its long-term behavior.
Event Horizon Telescope Collaboration; Akiyama, Kazunori; Alberdi, Antxon and 272 more
Affiliation:
Event Horizon Telescope Collaboration
Abstract:
In this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohydrodynamics simulations, including aligned, tilted, and stellar-wind-fed simulations; radiative transfer is performed assuming both thermal and nonthermal electron distribution functions. We test the models against 11 constraints drawn from EHT 230 GHz data and observations at 86 GHz, 2.2 μm, and in the X-ray. All models fail at least one constraint. Light-curve variability provides a particularly severe constraint, failing nearly all strongly magnetized (magnetically arrested disk (MAD)) models and a large fraction of weakly magnetized models. A number of models fail only the variability constraints. We identify a promising cluster of these models, which are MAD and have inclination i ≤ 30°. They have accretion rate (5.2-9.5) × 10-9 M ⊙ yr-1, bolometric luminosity (6.8-9.2) × 1035 erg s-1, and outflow power (1.3-4.8) × 1038 erg s-1. We also find that all models with i ≥ 70° fail at least two constraints, as do all models with equal ion and electron temperature; exploratory, nonthermal model sets tend to have higher 2.2 μm flux density; and the population of cold electrons is limited by X-ray constraints due to the risk of bremsstrahlung overproduction. Finally, we discuss physical and numerical limitations of the models, highlighting the possible importance of kinetic effects and duration of the simulations.
Monthly Notices of the Royal Astronomical Society, Volume 511, issue 1, 413-424
Authors:
Levshakov, S. A.; Agafonova, I. I.; Henkel, C.; Kim, Kee-Tae; Kozlov, M. G.; Lankhaar, B.; Yang, W.
Affiliation:
Abstract:
We estimate limits on non-universal coupling of hypothetical hidden fields to standard matter by evaluating the fractional changes in the electron-to-proton mass ratio, μ = me/mp, based on observations of Class I methanol masers distributed in the Milky Way disc over the range of the Galactocentric distances 4 ？？ R ？？ 12 kpc. The velocity offsets ？？V = V44 ？ V95 measured between the 44- and 95-GHz methanol lines provide, so far, one of the most stringent constraints on the spatial gradient kμ ≡ d(？？μ/μ)/dR < 2 × 10？9 kpc？1 and the upper limit on ？？μ/μ <2 × 10？8, where ？？μ/μ = (μobs ？ μlab)/μlab. We also find that the offsets ？？V are clustered into two groups which are separated by δ？？V = 0.022 ± 0.003 km s？1 (1σ confidence level). The grouping is most probably due to the dominance of different hyperfine transitions in the 44- and 95-GHz methanol maser emission. Which transition becomes favoured is determined by an alignment (polarization) of the nuclear spins of the four hydrogen atoms in the methanol molecule. This result confirms that there are preferred hyperfine transitions involved in the methanol maser action.
CTA 102 is a blazar implying that its relativistic jet points towards Earth and emits synchrotron radiation produced by energetic particles gyrating in the magnetic field. This study aims to figure out the physical origins of radio flares in the jet, including the connection between the magnetic field and the radio flares. The data set in the range of 2.6？343.5 GHz was collected o v er a period of ∼5.5 yr (2012 No v ember 20？2018 September 23). During the data collection period, seven flares at 15 GHz with a range of the variability time-scale of roughly 76？227 d were detected. The quasi-simultaneous radio data were used to investigate the synchrotron spectrum of the source. We found that the synchrotron radiation is self-absorbed. The turno v er frequenc y and the peak flux density of the synchrotron self-absorption (SSA) spectra are in the ranges of ∼42？172 GHz and ∼0.9？10.2 Jy, respectively. From the SSA spectra, we derived the SSA magnetic field strengths to be ∼9.20, ∼12.28, and ∼50.97 mG on 2013 December 24, 2014 February 28, and 2018 January 13, respectively. We also derived the equipartition magnetic field strengths to be in the range of ∼24？109 mG. The equipartition magnetic field strengths are larger than the SSA magnetic field strengths in most cases, which indicates that particle energy mainly dominates in the jet. Our results suggest that the flares in the jet of CTA 102 originated due to particle acceleration. We propose the possible mechanisms of particle acceleration.
1 Korea Astronomy and Space Science Institute, Daedeok-daero 776, Yuseong-gu, Daejeon 34055, Republic of Korea
2 University of Science and Technology, Gajeong-ro 217, Yuseong-gu, Daejeon 34113, Republic of Korea
3 Instituto de Astrofísica de Andalucía—CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, Spain; gyzhao@iaa.es
4 Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan
5 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
6 Kogakuin University of Technology & Engineering, Academic Support Center, 2665-1 Nakano, Hachioji, Tokyo 192-0015, Japan
7 Massachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USA
8 Black Hole Initiative at Harvard University, 20 Garden Street, Cambridge, MA 02138, USA
9 Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
10 Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
11 Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan
12 Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
13 Department of Astronomy, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul 03722, Republic of Korea
14 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
15 Department of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
16 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s Republic of China
17 Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008, People’s Republic of China
18 The Research Institute for Time Studies, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, Yamaguchi 753-8511, Japan
19 Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan, R.O.C.
20 Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea
21 Department of Physics and Astronomy, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul, Republic of Korea
22 Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, Yamaguchi 753-8511, Japan
23 SNU Astronomy Research Center, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea
24 Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
25 Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, People’s Republic of China
26 Toyo University, 5-28-20 Hakusan, Bunkyo-ku, Tokyo 112-8606, Japan
27 National Institute of Technology, Hachinohe College, Yubinbango Aomori Prefecture Hachinohe Oaza Tamonoki character Ueno flat 16-1, 039-1192, Japan 28 National Astronomical Research Institute of Thailand (Public Organization), 260 Moo 4, T. Donkaew, A. Maerim, Chiangmai, 50180, Thailand
29 Center for Astronomy, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
30 Basic Science Research Institute, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju, Chungbuk 28644, Republic of Korea
Abstract:
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.