An enormous black hole one hundred thousand times more massive than the sun has been found hiding in a toxic gas cloud wafting around near the heart of the Milky Way.
If the discovery is confirmed, the invisible behemoth will rank as the second largest black hole ever seen in the Milky Way after the supermassive black hole known as Sagittarius A* that is anchored at the very centre of the galaxy.
Astronomers in Japan found evidence for the new object when they turned a powerful telescope in the Atacama desert in Chile towards the gas cloud in the hope of understanding the strange movement of its gases. Unlike those that make up other interstellar clouds, the gases in this cloud – including hydrogen cyanide and carbon monoxide – move at wildly different speeds.
Observations from the Alma telescope in Chile showed that molecules in the elliptical cloud, which is 200 light years from the centre of the Milky Way and 150 trillion kilometres wide, were being pulled around by immense gravitational forces. The most likely cause, according to computer models, was a black hole no more than 1.4 trillion km across.
The scientists’ suspicion that a black hole lay in the midst of the gas cloud received a boost when further observations picked up radio waves indicative of a black hole coming from the centre of the cloud, said Tomoharu Oka, an astronomer at Keio University in Tokyo. “This is the first detection of an intermediate-mass black hole candidate in the Milky Way galaxy,” he said.
So-called intermediate-mass black holes fill a gap in astronomer’s knowledge of the most massive objects in the universe. The smallest black holes form when particular types of stars explode at the end of their lives. According to scientists’ calculations, the Milky Way is home to about 100m of these smaller black holes, though only about 60 have been spotted.
But astronomers also know that much larger, supermassive black holes lie at the heart of large galaxies including the Milky Way, where Sagittarius A* weighs as much as 4 million suns. What is unknown is how these supermassive black holes form.
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SOURCE: The Guardian, Ian Sample