The similarity between the black hole Sagittarius A* and the black hole in the galaxy M87 reveals shared physical properties and raises the possibility of the existence of a hidden jet
Earlier this year, the Event Horizon Telescope (EHT) collaboration released a new image that reveals strong, organized magnetic fields spiraling out from the rim of the supermassive black hole Sagittarius A*. This groundbreaking image of the Milky Way's central black hole, taken for the first time in polarized light, shows a structure of magnetic fields very similar to that of the black hole in galaxy M87.
This suggests that strong magnetic fields may be a common feature of all black holes. The similarity also raises the possibility of a hidden jet erupting from Sagittarius A*.
Researchers unveiled the first image of Sagittarius A* – about 27,000 light-years from Earth – in 2022, and found that although the size and mass of the Milky Way's supermassive black hole is more than a thousand times smaller than M87's black hole, it looks very similar. This has made scientists wonder if the two have common features that they don't see. To find out, the team decided to study Sagittarius A* in polarized light.
In previous studies of the light around M87* they found that the magnetic fields around the supermassive black hole allow it to launch powerful jets of matter back into its surroundings. Building on that research, the new images revealed that this may also be the case in Sagittarius A*.
"We now see that there are strong, coiled and organized magnetic fields near the black hole at the center of the Milky Way galaxy," said Sarah Issaun, co-leader of the study. "Together with the fact that Sagittarius A* has a polarization structure very similar to the structure seen in the much larger and more powerful black hole M87*, we discovered that strong and ordered magnetic fields are essential to how black holes interact with the gas and matter around them."
The scientists conclude from this image of the supermassive black holes M87* and Sagittarius A* seen in polarized light that the structure of their magnetic fields is similar. This is important because it suggests that the physical processes that determine how a black hole feeds and launches a jet may be universal properties among supermassive black holes.
Credit: EHT Collaboration
Light is an electromagnetic wave that oscillates, or moves, and allows us to see objects. Sometimes light oscillates in a perfect direction and this is called "polarization". Although polarized light surrounds us, the human eye does not distinguish between it and "normal" light. In the plasma around these black holes, particles swirling around magnetic lines impart a polarization pattern perpendicular to the field. This allows astronomers to see in ever clearer detail what is happening in black hole regions and to map their genetic field lines.
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