A new image from the Event Horizon Telescope (EHT) collaboration involving UCL's Dr Ziri Younsi has uncovered strong and organised magnetic fields spiralling from the edge of the supermassive black hole Sagittarius A* (Sgr A*).
Seen in polarised light for the first time, this new view of the monster lurking at the heart of the Milky Way galaxy has revealed a magnetic field structure strikingly similar to that of the black hole at the centre of the M87 galaxy, suggesting that strong magnetic fields may be common to all black holes. This similarity also hints toward a hidden jet in Sgr A*. The results were published today in The Astrophysical Journal Letters.
Scientists unveiled the first image of Sgr A*- which is approximately 27,000 light-years away from Earth - in 2022, revealing that while the Milky Way's supermassive black hole is more than a thousand times smaller and less massive than M87's, it looks remarkably similar.
This made scientists wonder whether the two shared common traits outside of their looks. To find out, the team decided to study Sgr A* in polarised light. Previous studies of light around M87* revealed that the magnetic fields around the black hole giant allowed it to launch powerful jets of material back into the surrounding environment. Building on this work, the new images have revealed that the same may be true for Sgr A*.
Dr Ziri Younsi, co-author of the new papers and a member of the EHT Science Council, said: "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.
"It is remarkable that the polarisation structure of Sgr A* is so similar to that of the M87 black hole, which we know possesses a prodigious relativistic jet. This exciting new study hints at the possibility of a jet hiding near the event horizon of Sgr A*."
Dr Sara Issaoun, co-lead of the project from the Center for Astrophysics, Harvard & Smithsonian, said: "What we're seeing now is that there are strong, twisted, and organised magnetic fields near the black hole at the centre of the Milky Way galaxy.
"Along with Sgr A* having a strikingly similar polarisation structure to that seen in the much larger and more powerful M87* black hole, we've learned that strong and ordered magnetic fields are critical to how black holes interact with the gas and matter around them."
