Submillimeter Quasi-Periodic Oscillations in Magnetically Choked Accretion Flows Models of Sgr A*

TL;DR

This study models submillimeter quasi-periodic oscillations in accretion flows around Sgr A* using simulations and radiative transfer, predicting observable signatures that can be tested with ALMA.

Contribution

It introduces a simulation-based model of polarized accretion flows around Sgr A* that predicts detectable sub-mm QPOs with specific properties.

Findings

QPOs have up to 5% flux amplitude and 2% polarized flux.

Oscillation period ~35 minutes matches BH magnetosphere rotation.

QPO signals are detectable at multiple frequencies and inclinations.

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.