CONSTRAINING THE FLARING REGION OF SAGITTARIUS A* BY 1.3 mm VLBI MEASUREMENTS

We use a model of an accretion flow coupled with an emergent flare to interpret the latest 1.3 mm very long baseline interferometry (VLBI) measurements for Sagittarius A*. The visibility data constrained the distances from the flare center to the black hole center as dEW ∼< 20 Rg and dNS ∼< 80 Rg in the east-west and north-south directions, respectively. If interpreted by the hot-spot model, the flare was preferred to pass in front of the black hole at a radius much larger than dEW. If interpreted by the episodic jet launched from a nearly edge-on hot accretion flow, the flare was preferred to be ejected with θj ∼> 40° off the black hole rotating axis. This method can be generalized to help us understand future submillimeter VLBI observations and study the millimeter/submillimeter variabilities in the vicinity of the Galactic center supermassive black hole.