Testing the Accretion Flow with Plasma Wave Heating Mechanism for Sagittarius a* by the 1.3MM Vlbi Measurements

TL;DR

This paper demonstrates that a plasma wave heating mechanism in a general relativistic accretion flow around Sgr A* aligns with recent 1.3mm VLBI observations, predicting observable black hole shadow features and enabling better geometric estimations.

Contribution

It introduces a plasma wave heating model for accretion flows around Sgr A* that matches polarization and VLBI data, and explores observational prospects with extended VLBI arrays.

Findings

The plasma wave heating model is consistent with polarization and VLBI observations.

Black hole shadow features could be observed with existing and future VLBI baselines.

Extended VLBI stations improve the estimation of the emission region's geometry.

Abstract

The vicinity of the supermassive black hole associated with the compact radio source Sagittarius (Sgr) A* is believed to dominate the observed emission at wavelengths near and shorter than $\sim$ 1 millimeter. We show that a general relativistic accretion flow, heated via the plasma wave heating mechanism, is consistent with the polarization and recent mm-VLBI observations of Sgr A* for an inclination angle of $\sim 45^\circ$, position angle of $\sim 140^\circ$, and spin $\lesssim 0.9$. Structure in visibilities produced by the black hole shadow can potentially be observed by 1.3 mm-VLBI on the existing Hawaii-CARMA and Hawaii-SMT baselines. We also consider eight additional potential mm-VLBI stations, including sites in Chile and New Zealand, finding that with these the basic geometry of the emission region can be reliably estimated.