February 16, 2023
Keio University
National Astronomical Observatory of Japan
Kanagawa University
A research team, composed of Miyuki Kaneko (a second-year master's student at the Graduate School of Science and Technology, Keio University), Professor Tomoharu Oka from the Department of Physics, Faculty of Science and Technology at the same university, the National Astronomical Observatory of Japan, and Kanagawa University, has discovered an isolated "Tadpole" molecular cloud near Sagittarius A* (Sgr A*), the nucleus of our Milky Way galaxy. It was revealed that this molecular cloud has an arc-like shape on the celestial sphere, and its line-of-sight velocity changes monotonically along this arc. This spatial velocity structure is extremely well reproduced by a Keplerian orbit around a point-like gravitational source, and the mass of this gravitational source was estimated to be 100,000 times that of the Sun. Furthermore, the absence of a corresponding object at other wavelengths indicates that this point-like gravitational source is not a dense star cluster or similar object. Currently, the possibility that the point-like gravitational source is an intermediate-mass black hole is considered the most likely. This object is believed to be the most reliable candidate for an intermediate-mass black hole discovered through the analysis of the distribution and kinematics of molecular gas.
The results of this research were published in the January 10 issue of the American astrophysics journal "The Astrophysical Journal".
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