We discovered two small high-velocity compact clouds ( HVCCs ) in HCN J =4–3 and J =3–2 maps of the central 20 pc of our Galaxy .
Both HVCCs have broad velocity widths ( \Delta V \gtrsim 40 km s ^ { -1 } ) and compact sizes ( d \sim 1 pc ) , and originate from the dense molecular clouds in the position–velocity space .
One of them has a faint counterpart in a Paschen- \alpha image .
Their spatial structure , kinematics , and absence of luminous stellar object are compatible with the notion that each of the small HVCCs is driven by the plunge of an invisible compact object into a molecular cloud .
Such objects are most likely inactive , isolated black holes .