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The Subaru Seminar is usually held in Room 104 of the Hilo Base Facility, adjacent to the main lobby. Everyone is welcome to attend. If you are interested in giving a seminar, please contact Subaru seminar organizers (Tomonori Usuda, Kumiko S. Usuda, Naoyuki Tamura) by email : (please change"_at" to @).

March 10th, Wednesday, at 11:00 am

" Quasi-Periodic Oscillations of the Accretion Disk around Sgr A* "

Makoto Miyoshi


I will talk about the detection of radio QPOs that may reflect structure in the disk around the supermassive black hole Sgr A*. Our data obtained with the Very Long Baseline Array (VLBA) at 43 GHz showed conspicuous periodic time variation that can be attributed to the disk structure with the periods of P = 16.8±1.4, 22.2±1.4, 31.2±1.5, 56.4±6 min, roughly in a 3 : 4 : 6 : 10 ratio. The first two periods correspond to a rotating one-arm structure, while the P = 31.4 min mode is consistent with a rotating 3-arm structure, when the disk is viewed edge-on. At the central region smaller than 50 micro-arcsec in radius, the P = 56.4 min period shows a double amplitude variation.

The spatial distribution of the oscillation periods suggest that the disk of Sgr A* is near edge-on and is rotating around a projected axis of PA = -10 degree. The observed VLBI images at 43 GHz may retain some features of the Sgr A* black hole accretion disk although the disk is obscured and blurred by the scattering of surrounding plasma.

Seminars are also held at JAC, CFHT, and IfA.

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