NAOJ: Tail of Stray Black Hole Hiding in the Milky Way

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NAOJ: Tail of Stray Black Hole Hiding in the Milky Way

Post by bystander » Thu Feb 02, 2017 6:27 pm

Tail of Stray Black Hole Hiding in the Milky Way
Nobeyama Radio Observatory | National Astronomical Observatory of Japan | 2017 Feb 02
[img3="Artist’s impression of a stray black hole storming through a dense gas cloud. The gas is dragged along by the strong gravity of the black hole to form a narrow gas stream. Credit: Keio University"]http://www.nro.nao.ac.jp/news/images/im ... a-Fig3.jpg[/img3][hr][/hr]
By analyzing the gas motion of an extraordinarily fast-moving cosmic cloud in a corner of the Milky Way, astronomers found hints of a wandering black hole hidden in the cloud. This result marks the beginning of the search for quiet black holes; millions of such objects are expected to be floating in the Milky Way although only dozens have been found to date. ...

During the survey, the team found a compact molecular cloud with enigmatic motion. This cloud, named the “Bullet,” has a speed of more than 100 km/s, which exceeds the speed of sound in interstellar space by more than two orders of magnitude. In addition, this cloud, with the size of two light-years, moves backward against the rotation of the Milky Way Galaxy. ...

The team proposed two scenarios for the formation of the Bullet. In both cases, a dark and compact gravity source, possibly a black hole, has an important role. One scenario is the “explosion model” in which an expanding gas shell of the supernova remnant passes by a static black hole. The black hole pulls the gas very close to it, giving rise to an explosion, which accelerates the gas toward us after the gas shell has passed the black hole. In this case, the astronomers estimated that the mass of the black hole would 3.5 times the solar mass or larger. The other scenario is the “irruption model” in which a high speed black hole storms through a dense gas and the gas is dragged along by the strong gravity of the black hole to form a gas stream. In this case, researchers estimated the mass of the black hole would be 36 times the solar mass or larger. With the present dataset, it is difficult for the team to distinguish which scenario is more likely. ...

Kinematics of Ultra-High-Velocity Gas in the Expanding Molecular Shell
Adjacent to the W44 Supernova Remnant
- Masaya Yamada et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

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