Signature of an intermediate-mass black hole in the central molecular zone of our galaxy

Abstract

The high-velocity compact cloud CO-0.40-0.22 was mapped in 22 molecular lines with the NRO 45 m radio telescope and the ASTE 10 m telescope. The map of each detected line shows that this cloud has a compact appearance (d≃3 pc) and extremely broad velocity width (Δ V≃100 km s-1). The representative position-velocity map along the major axis shows that CO-0.40-0.22 consists of an intense region with a shallow velocity gradient and a less intense high-velocity wing. This kinematical structure can be attributed to a gravitational kick to the molecular cloud caused by an invisible compact object with a mass of ∼105 M⊙. Its compactness and the absence of a counterpart at other wavelengths suggest that this massive object is an intermediate-mass black hole.