Why did scientist conclude that a black hole is the center of the Milky Way

Explanation:because eveything that went to the middle of the milky way dissapeard

while exploring a cloud of molecular gas located near the center of the Milky Way, in which the gas moved at vastly different speeds. As they studied the cloud, the researchers saw a clump of gas toward the center of the cloud that appeared to be moved around by massive gravitational forces.