01/16/2017
Keio University
A research team from Keio University, led by Masaya Yamada (a second-year master's student at the Graduate School of Science and Technology) and Professor Tomoharu Oka of the Department of Physics, Faculty of Science and Technology, used the National Astronomical Observatory of Japan's ASTE 10 m Telescope and the Nobeyama 45 m Radio Telescope to conduct radio spectroscopic observations of the "Bullet," an ultra-high-velocity molecular gas component discovered in the disk of the Milky Way galaxy, revealing its detailed spatial structure, motion, and physical state. The results showed that this Bullet was driven (set in motion) by a local phenomenon that occurred 5,000 to 8,000 years ago. Considering the Bullet's enormous kinetic energy, its spatial and velocity structure, and the fact that no celestial object is currently observed in this direction, it is highly likely that the driving source was a temporarily activated black hole. It is currently believed that 100 million to 1 billion black holes are floating in the Milky Way galaxy. This discovery is a groundbreaking finding that suggests the existence of "stray black holes"—those without companion stars—for which there have been no observational methods until now.
This research was published in the January 1 online edition of the American astrophysics journal "The Astrophysical Journal Letters."
Please see below for the full press release.