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Paper: Flux Variability of Sagittarius A* at Short mm-wavelengths
Volume: 402, Approaching Micro-Arcsecond Resolution with VSOP-2: Astrophysics and Technologies
Page: 376
Authors: Miyazaki, A.; Shen, Z.-Q.; Li, J.; Miyoshi, M.; Tsuboi, M.; Tsutsumi, T.
Abstract: We performed the monitoring observations of the flux density toward Sgr A*, which is a compact radio source associated with a super-massive black hole located at the dynamical center of the Galaxy, using the Nobeyama Millimeter Array (NMA) and the Australia Telescope Compact Array (ATCA) at mm-wavelengths. Since 1996, the flux monitoring observations using the NMA were carried out in the 3- and 2-mm bands. Then we detected several flares of Sgr A* with typical durations of a few weeks. We also found some intraday variations (IDVs) of Sgr A* in both observing bands. The 3-mm flux observations of Sgr A* using the ATCA in the southern hemisphere were also carried out to detect IDVs with a longer observing window. In the ATCA observations, we detected IDVs of Sgr A* with timescale of a few hour. In these IDVs, the short flux-doubling timescale was estimated to be a few hours, constraining the physical size of flare-emitting region within about a few tens of AU.
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