Sagittarius A, in polarized light. “What we are seeing now is that there are strong, distorted, organized magnetic fields near the black hole at the center of the Milky Way.”
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The image offers a never-before-seen view of the black hole at the center of our galaxy, as well as a clue that many or all black holes may share a pattern.
The Milky Way's supermassive black hole, nicknamed Sagittarius A* (pronounced Sagittarius star A), lies behind vast dust and stellar clouds. So most of what we know about this monster black hole comes from radio wavelengths, which can penetrate dust.
But today, March 27, 2024, we know a little more about the Milky Way's black hole. Astronomers just announced that they used the Event Horizon Telescope to capture the first image of our galaxy's giant black hole in polarized light.
This is the same telescope used to capture the first direct image of a supermassive black hole in 2019. The new image suggests that all black holes may have strong magnetic fields. It also suggests that our galaxy's black hole may harbor a hidden jet.
Sgr A* has a mass 4 million times greater than that of our Sun and is located about 26 thousand light years – the distance that light travels in a year, 5.9 trillion miles (9.5 trillion km) – of Earth.
“For a while, we’ve believed that magnetic fields play a key role in the way black holes feed on and eject matter in powerful jets,” said astronomer Sara Issaoun of the Center for Astrophysics – Harvard & Smithsonian and co-leader of the research. .
“This new image, along with a surprisingly similar polarization structure seen in the much larger and more powerful black hole M87*, shows that strong, orderly magnetic fields are essential for the interaction of black holes with the gas and matter around them. ,” Issaoun added.
Black holes are extraordinarily dense objects, with gravity so strong that not even light can escape, making them extremely challenging to view.
“The magnetic field appears to be organized in a spiral, similar to M87*. This geometry of the magnetic field implies that the black hole can generate very efficient jets that project into the galaxy,” said another of the researchers, astronomer at the Center for Astrophysics, Angelo Ricarte.
The new image, like previous images of Sgr A* and black hole M87, was obtained using the Event Horizon Telescope (EHT), an international scientific collaboration of a global network of observatories working collectively to observe radio sources associated with holes. blacks.
The event horizon of a black hole is the point of no return beyond which anything – stars, planets, gas, dust and all forms of electromagnetic radiation – is swept away into oblivion.
“By imaging polarized light from glowing hot gas near black holes, we are directly inferring the structure and strength of the magnetic fields that traverse the flow of gas and matter that the black hole feeds on and ejects,” Issaoun said.
“Compared to previous results, polarized light teaches us much more about astrophysics, the properties of gas and the mechanisms that occur when a black hole feeds,” Issaoun added.
Light is an oscillating electromagnetic wave that allows objects to be seen. Sometimes light oscillates in a specific orientation, and this is called polarized light.
Black hole M87 has a mass 6 billion times greater than that of our Sun and inhabits the center of a gigantic elliptical galaxy. It ejects a powerful jet of plasma, gas so hot that some or all of its atoms are split into subatomic particles, electrons and ions, visible at all frequencies.
Evidence of a jet flowing from Sgr A* is mounting, researchers said.
“One thing we are really excited about is the prediction of a powerful jet. As our instruments improve over the next few years, if it exists, we should be able to deduce it from the data,” Ricarte said.