An Approach Detecting the Event Horizon of Sgr A*

TL;DR

This paper demonstrates that submillimeter VLBI arrays, especially in the southern hemisphere, can effectively image the event horizon of Sgr A* and estimate its black hole mass through visibility analysis.

Contribution

It presents performance simulations showing that arrays with over 10 stations can produce good images of Sgr A* and that even small arrays can estimate the black hole's shadow size.

Findings

Good imaging possible with >10 station arrays

Small arrays can estimate black hole mass from visibility

Southern hemisphere arrays are crucial for Sgr A* imaging

Abstract

Imaging the vicinity of a black hole is one of the ultimate goals of VLBI astronomy. The closest massive black hole, Sgr A*, located at the Galactic center, is the leading candidate for such observations. Combined with recent VLBI recording technique and submillimeter radio engineering, we now have sufficient sensitivity for the observations. Here we show performance simulations of submillimeter VLBI arrays for imaging Sgr A*. Good images are obtained from submillimeter VLBI arrays in the southern hemisphere composed of more than 10 stations. We also note that even with a small array, we can estimate the shadow size and then the mass of the black hole from visibility analysis. Now, all we need is to construct a submillimeter VLBI array in the southern hemisphere if we wish to unveil the black hole environment of Sgr A*. Key words: black hole, event horizon, Sgr A*, submillimeter