The black hole at the centre of our galaxy, known as Sagittarius A*, has been captured in polarised light to reveal its magnetic field
By Alex Wilkins
27 March 2024
The black hole Sagittarius A*, viewed in polarised light
European Southern Observatory (ESO)
This is the supermassive black hole at the centre of our galaxy as we have never seen it before. The image reveals the swirling magnetic fields around Sagittarius A* (Sgr A*) and hints that it may be producing a jet of high-energy material, which astronomers have yet to see.
The picture was taken by a network of observatories around the world operating as a single, giant telescope, called the Event Horizon Telescope (EHT). In 2022, it produced the first image of Sgr A*, revealing light coming from whirling hot plasma set against the dark background of the black hole’s event horizon, where light can’t escape its extreme gravity.
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Now, EHT researcher Ziri Younsi at University College London and his colleagues have measured how this light is polarised, or the orientation of its electromagnetic field, showing the direction and strength of the magnetic field around Sgr A*.
The image is remarkably similar to the magnetic field of M87*, the first black hole EHT studied. Given that M87* is around 1500 times more massive than Sgr A*, it suggests that supermassive black holes may have similar structures regardless of their size, says Younsi.
The two black holes imaged by the Event Horizon Telescope look surprisingly similar European Southern Observatory (ESO)