Surprising images of black hole at centre of Milky Way alter our understanding of black holes

New Delhi, India

Two years after we became aware of the existence of Sagittarius A*, a giant black hole at the centre of the Milky Way, the Event Horizon Telescope captured it in polarised light for the first time and it gave some fascinating insights.

The image shows neatly ordered swirling polarisation lines around the black hole named Sagittarius A*.

These lines are directly related to the magnetic field around the black hole. This new research is published in the journal The Astrophysical Journal Letters in collaboration with Event Horizon Telescope (EHT).

What does the Sagittarius A* image reveal?

The polarisation lines are seen when magnets align in a particular direction to create a stronger and more organised magnetic field around the object, in this case, Sagittarius A*.

The magnetic fields are generated by charged particles around the black hole.

“This spiral pattern that we see swirling around the black hole indicates that the magnetic fields must also be a spiral pattern whirling around – and that they're very strong and very ordered,” Dr Sara Issaoun, co-lead of the project was quoted as saying by the BBC.

Why is this discovery important?

The speculation of a magnetic field surrounding a black hole is common among scientists.

Then what makes this research so important? The team of researchers noticed that the magnetic fields around Sgr A* are comparable to another much bigger black hole, M87*.

The remarkable similarity between the magnetic fields of black holes Sgr A* and 1000 times larger M87* leads to the speculation that strong magnetic fields could be a fundamental property of all massive black holes regardless of differences in their size.

Dr Sara Issaoun told BBC, “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."

Sagittarius A* weighs as much as four million suns and is 27,000 light-years away from Earth. The first picture of the black hole Sagittarius A*, or Sgr A* was released back in 2022. 

How did Event Horizon Telescope capture Sgr A*?

Event Horizon Telescope used a network of eight telescopes from all around the world since a single telescope wouldn’t have been powerful enough to observe Sgr A*. Data from these eight telescopes, along with timestamps were combined using supercomputers to produce the final images.