Possible brightening at 22 GHz of Sgr A*
ATel #5013; M. Tsuboi, Y. Asaki(ISAS/JAXA), Y. Yonekura(Ibaraki Univ.), H. Kaneko, Y. Miyamoto, M. Seta, N. Nakai(Univ. of Tsukuba), O. Kameya, M. Miyoshi(NAOJ), H. Takaba, K. Wakamatsu(Gifu Univ.), Y. Fukuzaki(GSI), T. Morimitsu(Univ. of Tokyo), M. Sekido(NICT), T. Oka, S. Takekawa (Keio Univ.), T. Omodaka, T. Handa(Kagoshima Univ.), and A. Takumi(OUJ)
on 26 Apr 2013; 13:00 UT
Credential Certification: Masato TSUBOI (tsuboi@vsop.isas.jaxa.jp)
Subjects: Radio, Black Hole, Transient
We report a possible brightening at 22 GHz of Sgr A* during daily monitoring observations with a short-baseline VLBI (Mizusawa10-m RT, Takahagi32-m RT, Tsukuba32-m RT, and Gifu11-m RT) which is a subset of the Japanese VLBI Network. This purpose of the monitor is to search the increase of 22-GHz emission from Sgr A* induced by the interaction of the G2 cloud with the accretion disk (Gillessen et al. 2012, Nature, 481, 51). The average flux density at 22 GHz of Sgr A* was 1.05+-0.16 Jy (preliminary) in the observing period in February and March 2013 (ATel #4923). The error is scattering of the data in the period. The flux density was gradually increased. The average flux density in DOY=105-113 d is 1.55+-0.18 Jy (preliminary). Because the amplitude of the brightening can be still explained by usual variability of Sgr A*, the relationship between the brightening and the X-ray flare detected by Swift (ATel #5006, #5008) is not clear for the present. We will continue the daily monitoring observations of Sgr A*.
