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 : sseminar_at_subaru.naoj.org (please change"_at" to @).
March 10th, Wednesday, at 11:00 am
" Quasi-Periodic Oscillations of the Accretion Disk around Sgr A* "
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
Seminars are also held at JAC,