Astronomers using the Event Horizon Telescope released the most detailed black hole image yet. It shows the cosmic body in polarized light.
The Event Horizon Telescope (EHT) collaboration, which produced the first-ever image of a black hole, has now revealed a new view of the massive object at the center of the Messier 87 (M87) galaxy.
The new image reveals how the M87 central supermassive black hole looks in polarized light.
This is the first time astronomers have been able to measure polarization, a signature of magnetic fields, this close to the edge of a black hole. This can help us better understand how the black hole shoots bright jets of energy across interstellar and intergalactic space.
The M87 galaxy lies 55 million light-years away in the constellation Virgo. The supermassive black hole at the center of it is a monster 6.5 billion times as massive as the sun.
On 10 April 2019, the EHT team released the first-ever image of a black hole. Thus, revealing a bright ring-like structure with a dark central region—the black hole’s shadow. It looks like a fuzzy smoke ring, much as Albert Einstein’s equations had predicted a century ago.
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Since then, the team has extracted more data from their observations about the radio waves’ polarization. The new image used polarized light, filtering it, much like polarized sunglasses, to show the area around the black hole. This revealed the shape of the magnetic fields in the hot gas swirling around the hole.
“This work is a major milestone: The polarization of light carries information that allows us to better understand the physics behind the image we saw in April 2019, which was not possible before,” explains Iván Martí-Vidal, also coordinator of the EHT Polarimetry Working Group and GenT distinguished researcher at the University of Valencia, Spain.
“Unveiling this new polarized light image required years of work due to the complex techniques involved in obtaining and analyzing the data,” he continued.
The mysterious bright jets of energy extend some 5,000 light-years from the center of M87. Most of the matter near the surface of the black hole falls in. Meanwhile, other particles escape moments before falling in and are blown far out into space in the form of jets.
The weird part is that astronomers still don’t understand exactly how jets larger than the galaxy itself are shot from its central region which is comparable in size to the solar system, nor how, exactly, matter falls into the black hole.
But the new study sheds light on the structure of the magnetic fields just outside the black hole. The team found that only theoretical models featuring strongly magnetized gas can explain what they are seeing.
The Event Horizon Telescope photos provide hints that the bright jet in M87 is actually powered from the rotational energy of the black hole, which twists the magnetic fields as it rotates.
As the particles spiral into the black hole, they drag the magnetic fields causing them to twist. Eventually, the magnetic fields become so strong that instead of the particles dragging, the magnetic field accelerates the particles toward the poles. They then go flying out in the form of jets.
“The observations suggest that the magnetic fields at the black hole’s edge are strong enough to push back on the hot gas and help it resist gravity’s pull. Only the gas that slips through the field can spiral inward to the event horizon,” explains Jason Dexter, assistant professor at the University of Colorado Boulder, US, and coordinator of the EHT Theory Working Group.
Astronomers were also able to estimate the rate at which the black hole is feeding on its environment. It turns out the supermassive beast isn’t too hungry; the black hole is eating “a tiny” one-thousandth of the mass of the sun per year.
Launched in 2009, the EHT collaboration is a multinational effort involving some 300 scientists. It uses a network of radio telescopes around the world to study black holes. The impressive resolution obtained with the EHT is equivalent to that needed to measure the length of a credit card on the surface of the moon.
However, the next step may be more than just an image.
The EHT team is designing a next-generation EHT that will enable scientists to make the first black hole movies.