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.

9 Pages, 4 Figures, accepted for publication in ApJ

References in corpus (7)

• Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre
• An Unambiguous Detection of Faraday Rotation in Sagittarius A*
• Polarimetry of near-infrared flares from Sagittarius A*
• A polarised infrared flare from Sagittarius A* and the signatures of orbiting plasma hotspots
• Imaging the Supermassive Black Hole Shadow and Jet Base of M87 with the Event Horizon Telescope
• GRAVITY: getting to the event horizon of Sgr A*
• Linearly and Circularly Polarized Emission in Sagittarius A*

Cited by in corpus (6)

• The Event Horizon Telescope: exploring strong gravity and accretion physics
• Dynamical Imaging with Interferometry
• Demonstrating Photon Ring Existence with Single-Baseline Polarimetry
• Forward Ray Tracing and Hot Spots in Kerr Spacetime
• Probing the Spacetime Around Supermassive Black Holes with Ejected Plasma Blobs
• Investigating the Disk-Jet Structure in M87 through Flux Separation in the Linear and Circular Polarization Images