Relative Astrometry of Compact Flaring Structures in Sgr A* with Polarimetric VLBI

Abstract

We demonstrate that polarimetric interferometry can be used to extract precise spatial information about compact polarized flares of Sgr A*. We show that, for a faint dynamical component, a single interferometric baseline suffices to determine both its polarization and projected displacement from the quiescent intensity centroid. A second baseline enables two-dimensional reconstruction of the displacement, and additional baselines can self-calibrate using the flare, enhancing synthesis imaging of the quiescent emission. We apply this technique to simulated 1.3-mm wavelength observations of a "hot spot" embedded in a radiatively inefficient accretion disk around Sgr A*. Our results indicate that, even with current sensitivities, polarimetric interferometry with the Event Horizon Telescope can achieve ~5 microarcsecond relative astrometry of compact flaring structures near Sgr A* on timescales of minutes.

arXiv comment9 Pages, 4 Figures, accepted for publication in ApJ

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• Demonstrating Photon Ring Existence with Single-Baseline Polarimetry
• Information Geometry on the Space of Equilibrium States of Black Holes in Higher Derivative Theories
• Gravitational Lensing of a star by a rotating black hole
• Forward Ray Tracing and Hot Spots in Kerr Spacetime
• Probing the Spacetime Around Supermassive Black Holes with Ejected Plasma Blobs
• Measuring the Direction and Angular Velocity of a Black Hole Accretion Disk via Lagged Interferometric Covariance
• Investigating the Disk-Jet Structure in M87 through Flux Separation in the Linear and Circular Polarization Images
• Visible shapes of black holes M87* and SgrA*