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Monitoring the Size and Flux Density of Sgr A* during the Active State in 2019 with East Asian VLBI Network

Authors :
Cheng, Xiaopeng
Cho, Ilje
Kawashima, Tomohisa
Kino, Motoki
Zhao, Guang-Yao
Algaba, Juan-Carlos
Kofuji, Yutaro
Lee, Sang-Sung
Lee, Jee-Won
Cheong, Whee Yeon
Jiang, Wu
Oh, Junghwan
Publication Year :
2023

Abstract

In this work, we studied the Galactic Center supermassive black hole (SMBH), Sagittarius A* (Sgr A*), with the KVN and VERA Array (KaVA)/East Asian VLBI Network (EAVN) monitoring observations. Especially on 13 May 2019, Sgr A* experienced an unprecedented bright near infra-red (NIR) flare; so, we find a possible counterpart at 43 GHz (7 mm). As a result, a large temporal variation of the flux density at the level 15.4%, with the highest flux density of 2.04 Jy, is found on 11 May 2019. Interestingly, the intrinsic sizes are also variable, and the area and major-axis size show a marginal correlation with flux density with >2{\sigma}. Thus, we interpret that the emission region at 43 GHz follows the larger-when-brighter relation in 2019. The possible origins are discussed with an emergence of a weak jet/outflow component and the position angle change of the rotation axis of the accretion disk in time.<br />Comment: 15 pages, 7 figures, 3 tables, Published in the Galaxies Special Issue "Challenges in Understanding Black Hole Powered Jets with VLBI"

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.2303.04421
Document Type :
Working Paper
Full Text :
https://doi.org/10.3390/galaxies11020046