Discovered Concealed Black Hole

Astronomers have made a significant discovery by identifying a stealthy black hole through its impact on an interstellar gas cloud. This particular black hole falls into the category of intermediate-mass black holes, which are estimated to be present in the galaxy in numbers exceeding 100 million. These findings not only introduce a fresh approach to detecting hidden black holes but also contribute to our understanding of how black holes grow and evolve.

Black holes possess an incredibly powerful gravitational force that prevents anything, including light, from escaping once it crosses the event horizon. Since black holes do not emit light, astronomers rely on the gravitational effects they exert on surrounding objects to infer their existence. Black holes vary in mass, ranging from approximately five times the mass of the sun to supermassive black holes millions of times larger. It has been theorized that small black holes merge and gradually increase in size, but until now, no intermediate-mass black hole weighing hundreds or thousands of times the mass of the sun had been discovered.

A research team led by Shunya Takekawa at the National Astronomical Observatory of Japan made an intriguing observation regarding HCN-0.009-0.044, a gas cloud exhibiting peculiar movement near the center of the galaxy, located 25,000 light-years away from Earth in the Sagittarius constellation. Utilizing the ALMA (Atacama Large Millimeter/submillimeter Array), the team conducted high-resolution observations of the cloud and determined that it revolves around an immense invisible object.

Takekawa explains, “Through detailed kinematic analyses, we have determined that an enormous mass, equivalent to 30,000 times that of the sun, is concentrated within an area much smaller than our solar system. This, coupled with the absence of any observable object in that location, strongly indicates the presence of an intermediate-mass black hole. By studying other anomalous clouds, we aim to uncover additional silent black holes.”

Tomoharu Oka, a coleader of the team and a professor at Keio University, emphasizes the importance of discovering this intermediate mass black hole in close proximity to the supermassive black hole located at the galactic center, a mere 20 light-years away. The future trajectory of this black hole suggests that it will eventually be absorbed by the supermassive black hole, similar to how gas is presently being drawn into it. This finding provides further evidence in support of the merger model of black hole growth.

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