黑洞，这一宇宙中的神秘天体，按其质量大小，主要可分为恒星级黑洞、超大质量黑洞以及中等质量黑洞三大类，前 两类黑洞之普遍存在已为学界所公认。然而，人们对“中等质量黑洞”是否存在的问题则始终未达成共识。

 Empirical evidence for both stellar-mass black holes and supermassive black holes is well established. However, it is not the case for intermediate-mass black hole. There has not yet got the unanimous conclusion about the problem whether central IMBHs in globular clusters exist or not.