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Millimeter VLBI observations of Sgr A* with KaVA and KVN

Published online by Cambridge University Press:  09 February 2017

G.-Y. Zhao ,
M. Kino ,
I.-J. Cho ,
K. Akiyama ,
B. W. Sohn ,
T. Jung ,
J. C. Algaba ,
K. Hada ,
Y. Hagiwara  and
J. Hodgson
...Show all authors
G.-Y. Zhao
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr
M. Kino
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr
I.-J. Cho
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr University of Science & Technology, 217 Gajeong-ro, Daejeon, Korea
K. Akiyama
Affiliation:
MIT, Haystack Observatory, Route 40, Westford, MA 01886, USA National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
B. W. Sohn
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr University of Science & Technology, 217 Gajeong-ro, Daejeon, Korea
T. Jung
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr University of Science & Technology, 217 Gajeong-ro, Daejeon, Korea
J. C. Algaba
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr
K. Hada
Affiliation:
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
Y. Hagiwara
Affiliation:
Toyo University, 5-28-20, Hakusan, Bunkyo-ku, Tokyo 112-8606, Japan
J. Hodgson
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr
M. Honma
Affiliation:
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
N. Kawaguchi
Affiliation:
Shanghai Astronomical Observatory, CAS, 80 Nandan Road, Shanghai 200030, China
S. Koyama
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, Bonn, 53121, Germany
J. A. Lee
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr University of Science & Technology, 217 Gajeong-ro, Daejeon, Korea
T. Lee
Affiliation:
Seoul National University, Seoul 151-742, Korea
K. Niinuma
Affiliation:
Yamaguchi University, Yoshida 1677-1, Yamaguchi, Yamaguchi 753-8512, Japan
J. Oh
Affiliation:
Seoul National University, Seoul 151-742, Korea
J.-H. Park
Affiliation:
Seoul National University, Seoul 151-742, Korea
H. Ro
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr Yonsei University, 134 Shinchondong, Seodaemungu, Seoul 120-749, Korea
S. Sawada-Satoh
Affiliation:
Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
F. Tazaki
Affiliation:
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
S. Trippe
Affiliation:
Seoul National University, Seoul 151-742, Korea
K. Wajima
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr
H. Yoo
Affiliation:
Korea Astronomy and Space Science Institute, Daedeokdae-ro 776, Daejeon 305-348, Korea email: gyzhao@kasi.re.kr Yonsei University, 134 Shinchondong, Seodaemungu, Seoul 120-749, Korea
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Abstract

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We present recent observation results of Sgr A* at millimeter obtained with VLBI arrays in Korea and Japan.

7 mm monitoring of Sgr A* is part of our AGN large project. The results at 7 epochs during 2013-2014, including high resolution maps, flux density and two-dimensional size measurements are presented. The source shows no significant variation in flux and structure related to the G2 encounter in 2014. According to recent MHD simulations by kawashima et al., flux and magnetic field energy can be expected to increase several years after the encounter; We will keep our monitoring in order to test this prediction.

Astrometric observations of Sgr A* were performed in 2015 at 7 and 3.5 millimeter simultaneously. Source-frequency phase referencing was applied and a combined ”core-shift” of Sgr A* and a nearby calibrator was measured. Future observations and analysis are necessary to determine the core-shift in each source.

Keywords

Galaxy: centerGalaxies: nucleiIndividual: Sgr A*techniques: interferometrictechniques: phase-referencing
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S322: The Multi-Messenger Astrophysics of the Galactic Centre , July 2016 , pp. 56 - 63
Copyright
Copyright © International Astronomical Union 2017 

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