Zhi-Qiang Shen and researchers at the Shanghai Astronomical Observatory captured radio waves emitted just beyond the edge of the mysterious object, known as Sagittarius A, with a system of 10 radio telescopes spread across the United States.
In a report in the science journal Nature they said it "provides strong evidence that Sgr A is a super-massive black hole."
The celestial objects that suck in everything around them including light are among the most mysterious objects in the universe. They are formed when matter from a dying star collapses under its own gravity.
Black holes have been described as the ultimate victory over gravity because of their ability to suck in stars and other galactic features.
Scientists have long suspected the presence of a black hole in the center of the Galaxy. Astronomers believe it is four million times more massive than our Sun.
The research reported in Nature suggests the black hole is as wide as the radius of the Earth's orbit.
"These observations provide strong evidence that Sgr A is indeed a black hole, and afford a glimpse of the behavior of the matter that is about to flow into it," said Christopher Reynolds, of the University of Maryland in the United States, in a commentary in the journal.
He described the findings as a further step toward capturing an image of the shadow around the edge of a black hole, which would be a classic test of Albert Einstein's general theory of relativity.
The theory predicts that massive bodies -- planets, stars or black holes -- actually twist time and space around as they spin.