WASHINGTON: The Milky Way, like most galaxies, has a supermassive black hole sitting right in its centre. Now, for the first time, scientists have detected a magnetic field just outside the event horizon – or outer boundary – of that black hole. Why do we care? Because that magnetic field is probably what makes our neighbourhood black hole so powerful.
It shouldn’t come as a surprise to you that black holes “suck” stars in and tear them apart. But the process doesn’t actually work as simply as vacuuming up some dust. Lots of matter is able to orbit the black hole at a safe distance, creating a flat disk full of all sorts of cosmic goodies. But this so-called accretion disk is magnetised, and the hot, turbulent conditions cause all sorts of wonky interactions between the different magnetic fields. These interactions are thought to be critical to the black hole’s ability to acquire matter – and to its ability to turn that matter into intense radiation that jets into space, shaping surrounding galaxies.
“Understanding these magnetic fields is critical. Nobody has been able to resolve magnetic fields near the event horizon until now,” Michael Johnson, of the Harvard-Smithsonian Centre for Astrophysics, the lead author of a paper on the findings published on Thursday in Science, said in a statement.
To find evidence of these magnetic fields around Sagittarius A, the black hole at the centre of our galaxy, scientists needed a telescope as big as Earth itself. Well, not a telescope, exactly: They used the Event Horizon Telescope (EHT), which is a network of radio telescopes across the globe. When you put all those radio telescopes together into one massive array, you can see some really hard to spot stuff – including compact black holes.
