'Recoiling' black hole in a nearby star cluster keeps slipping detection, baffling scientists

Scientists have discovered a black hole at the centre of a bright cluster of a distant galaxy that has baffled them for its ‘recoiling’ nature. The enormous black hole keeps slipping through the astronomers’ nets. The galaxy, at the core of the cluster Abell 2261, about 2.7 billion light-years from Earth, should have a large central black hole, weighing as much as 3 billion to 100 billion suns, according to scientists. However, strangely enough the supermassive black hole has evaded detection so far. Researchers said they have previously used X-rays streaming from the galaxy’s centre, since they are potential black-hole signatures. As material falls into a black hole’s maw, it accelerates and heats up tremendously, emitting lots of high-energy X-ray light. Now, scientists have conducted an even deeper search for X-rays using Chandra X-ray Observatory, that even considered the possibility that the black hole was knocked toward the vicinities after a monster galactic merger. According to scientists, when black holes and other massive objects collide, they throw off ripples in space-time known as gravitational waves. However, if the emitted waves are not symmetrical in every direction, they could very well push the merged supermassive black hole away from the centre. [caption id=“attachment_6823581” align=“alignnone” width=“1280”] Streamlines showing magnetic fields layered over a color image of the dusty ring around the Milky Way’s massive black hole. Image credit: NASA/SOFIA/Hubble Space Telescope[/caption] Such recoiling black holes are however, hypothetical creatures since no one has definitively spotted one till date. According to researchers, Abell 2261’s central galaxy could be a good place to study them, since it shows signs of a dramatic merger. The new study was carried out by a team of researchers led by Kayhan Gultekin from the University of Michigan. They found that the densest concentrations of hot gas were not in the galaxy’s central regions. But the Chandra data didn’t reveal any significant X-ray sources, either in the galactic core or in big clumps of stars farther afield. So the mystery of the missing supermassive black hole persists. The mystery could be solved by the James Webb Space Telescope, scheduled for launch in October 2021. However, if it too does not spot a black hole at the centre of the galaxy, then the only plausible explanation is that it has recoiled well out of the centre of the galaxy. The new study is published in the journal of the American Astronomical Society.