“Dark Gateways” –Hidden in the Milky Way

intermediate mass black hole


This past February, a hidden intermediate mass black hole–a one-way door out of our universe– 30,000 times mass of the Sun, was detected packed in a region much smaller than our Solar System only 20 light-years from the supermassive black hole at the Galactic center. The stealth object was detected from its effects on an interstellar gas cloud. This intermediate mass black hole is one of over 100 million quiet black holes hidden in the Milky Way.

“The gates of hell, the end of space and time,” is how black holes were described by Ellie Mae O’Hagan for The Guardian. “Everything unfortunate enough to get too close to it falls in and never emerges again, including light itself. It’s the point at which every physical law of the known universe collapses. Perhaps it is the closest thing there is to hell: it is an abyss, a moment of oblivion.”

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Because black holes do not emit light, astronomers must infer their existence from the effects their gravity produce in other objects. Black holes range in mass from about 5 times the mass of the Sun to supermassive black holes millions of times the mass of the Sun. Astronomers think that small black holes merge and gradually grow into large ones, but no one had ever found an intermediate mass, hundreds or thousands of times the mass of the Sun.

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A research team led by Shunya Takekawa at the National Astronomical Observatory of Japan noticed HCN–0.009–0.044, a gas cloud moving strangely near the center of the Galaxy 25,000 light-years away from Earth in the constellation Sagittarius. They used ALMA (Atacama Large Millimeter/submillimeter Array) to perform high resolution observations of the cloud and found that it is swirling around an invisible massive object.

“Detailed kinematic analyses revealed that an enormous mass, 30,000 times that of the Sun, was concentrated in a region much smaller than our Solar System,” said Takekawa. “This and the lack of any observed object at that location strongly suggests an intermediate-mass black hole. By analyzing other anomalous clouds, we hope to expose other quiet black holes. ”

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Tomoharu Oka, a professor at Keio University and coleader of the team, adds, “It is significant that this intermediate mass black hole was found only 20 light-years from the supermassive black hole at the Galactic center. In the future, it will fall into the supermassive black hole; much like gas is currently falling into it. This supports the merger model of black hole growth.”

The Daily Galaxy, Sam Cabot, via ALMA Observatory