2016ApJ...816L...7O

We mapped the high-velocity compact cloud CO-0.40-0.22 in 21 molecular lines in the 3 mm band using the Nobeyama Radio Observatory 45 m radio telescope. Eighteen lines were detected from CO-0.40-0.22. The map of each detected line shows that this cloud has a compact appearance (d ~= 3 pc) and extremely broad velocity width (ΔV ~= 100 km/s). The mass and kinetic energy of CO-0.40-0.22 are estimated to be 10^3.6 M_☉ and 10^49.7 erg, respectively. 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. Here, we show that 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 counterparts at other wavelengths suggest that this massive object is an intermediate-mass black hole.