Magnetic structure of black hole at centre of Milky Way revealed

Scientists have discovered that Sagittarius A*, the supermassive black hole at the centre of the Milky Way, has a magnetic field pattern similar to the black hole of the M87 galaxy.

The black hole seen in polarised light for the first time. (UCL)

A new image released by the University College London on Wednesday reveals the heart of Sagittarius A*, the supermassive black hole lying at the centre of the Milky Way for the first time. The image shows that its magnetic field structure is similar to that of the black hole at the centre of the M87 galaxy, suggesting that all black holes may have similarly strong magnetic fields.

The results of the research were published in The Astrophysical Journal Letters and also hints at the existence of a hidden jet on the black hole. The black hole is approximately 27,000 light-years away from the planet, and scientists also explored whether they share traits apart from their appearance.

Previous studies of light around the M87 black hole revealed that its magnetic fields allowed it to launch powerful jets of material back into the environment. The new research suggests the same may be true for Sagittarius A*. Apart from the fact that it has a similar polarisation structure to the much larger and more powerful M87* black hole, the researchers also found that strong and ordered magnetic fields are critical to how black holes interact with the gas and matter around them.

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“It is very exciting to see the first polarised images of the black hole in the heart of our galaxy. These observations reveal much more information about the magnetic fields surrounding the black hole, and will improve our ability to model accreting black holes in the future,” said Ziri Younsi, co-author of the new papers and a member of the EHT Science Council, in a press statement.

Light is an oscillating electromagnetic wave that helps us see objects. Sometimes, light oscillates in just one orientation, which is what is referred to as “polarised” light. The plasma around these black holes has particles whirling around magnetic fields, giving the light a polarisation pattern perpendicular to the field. This allows astronomers see what is happening in black hole regions, letting them map magnetic field lines.