Submillimeter Quasi-Periodic Oscillations in Magnetically Choked
Accretion Flows Models of Sgr A*
release_2p3brikiizdcvetipjqgw4u2be
by
Roman V. Shcherbakov,
Jonathan C. McKinney
2013
Abstract
High-frequency quasi-periodic oscillations (QPOs) appear in
general-relativistic magnetohydrodynamic simulations of magnetically choked
accretion flows around rapidly rotating black holes (BHs). We perform polarized
radiative transfer calculations with ASTRORAY code to explore the
manifestations of these QPOs for SgrA*. We construct a simulation-based model
of a radiatively inefficient accretion flow and find model parameters by
fitting the mean polarized source spectrum. The simulated QPOs have a total
sub-mm flux amplitude up to 5% and a linearly polarized flux amplitude up to
2%. The oscillations reach high levels of significance 10-30\sigma and high
quality factors Q~5. The oscillation period T~100M~35min corresponds to the
rotation period of the BH magnetosphere that produces a trailing spiral in
resolved disk images. The total flux signal is significant over noise for all
tested frequencies 87GHz, 230GHz, and 857GHz and inclination angles 10deg,
37deg, and 80deg. The non-detection in the 230GHz Sub-Millimeter Array light
curve is consistent with a low signal level and a low sampling rate. The
presence of sub-mm QPOs in SgrA* will be better tested with the Atacama Large
Millimeter Array.
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