At the heart of a giant galaxy 55 million light-years away, a black hole with 6.5 billion suns casts a fountain of matter at near-light speed into the cosmos. Using an array called the Event Horizon Telescope (EHT), scientists have used radio waves to capture a photograph of the black hole, and we offer our very first look at the extreme environment near its edge in 2019.
Two years later, the international team that delivered the stunning image, along with additional partners, published the results of a 2017 observation campaign that examined the host system, Messier 87, in various wavelengths.
The report, published today in The Astrophysical Journal, contains data from 19 Earth and space-based observatories, and was written by more than 750 scientists. It describes a more complete view of the supermassive black hole and its massive ray, allowing scientists to take a good look at how magnetic fields, particles, gravity and radiation interact on various scales in the vicinity of a supermassive black hole.
‘This is the kitchen of physics, right? Everything is there, ”said McGill University Daryl Haggard, who helped coordinate the observations with more wavelengths. “We’re really starting to see orbits, we’re looking right next to the black hole and exploring this exotic environment.”
“I think this is one of the articles that really connects EHT with the rest of the community. It’s a foretaste of what the facility is actually meant to do,” adds team member Sera Markoff of the University of Amsterdam. “I feel like it’s at the beginning of it all.”
Now the EHT team is in the midst of an important twelve-day observation run – the first they have been able to do since 2018 due to technical problems and the coronavirus pandemic. This time, the collaboration added three new telescopes in the wake of observatories, including a facility in Greenland, and it again scans the air in wavelengths that span the electromagnetic spectrum – as long as the weather works together.
“You have to have really nice weather in all areas,” says Radboud University’s Monika Moscibrodzka. “And the more websites you have, the smaller the chance of good weather at each of them.”
A cosmic curler
Black holes have been among the more intriguing, compelling astronomical phenomena for more than a century, capturing our imagination with their extreme physics and the fact that what goes in never comes out again. But these cosmic sinkholes have only recently come into focus, thanks to the EHT image, as well as the Nobel Prize-winning studies of objects zipping around the supermassive black hole at the core of the Milky Way and a wealth of information obtained when black holes collide. .
“In the last few years, we have gone from black holes that are science fiction to black holes that are a reality,” says Marta Volonteri of the Institut d’Astrophysique de Paris.
The Event Horizon Telescope actually consists of several radio telescopes spread all over the world, from Greenland to the South Pole, which act together as an observatory on earth. To make these images of M87’s supermassive black hole, an enormous amount of data has to be combined – so much data that the team cannot transmit it digitally and instead have to drop hard drives by mail.
When the team unveiled their first image in April 2019, scientists were stunned because the object looked almost exactly as predicted by a century-old theory.
The image of M87 offers the chance to test Einstein’s general theory of relativity of 1915, which states that what we experience as gravity emerges when matter bends the fabric of space-time. The environment around M87’s heart is intense – a hot jumble of extreme gravity, magnetic fields and particles – making it one of the best places in the universe to challenge general relativity.
“Everyone is always trying to break through these theories because we learn so much when we get a knock in the armor,” Haggard says. “We like to break models. But we have not yet successfully broken the general relativity. ‘
While general relativity prevailed again with M87, the EHT image quickly worked its way into the public consciousness. The brain-like cartoon XKCD showed the team several times and placed the solar system on top of the black hole’s stocking to show its extent. Others compare his glowing ring to the Eye of Sauron of The Lord of the Rings movies. But the most energetic debate has arisen over the similarity with breakfast food.
“Is it more like a bagel or a donut?” Ask Volunteers.
An update to the original image, compiled by Moscibrodzka and her colleagues, resolved the argument last month: the black hole looks like a curler or a grooved donut. In the newer picture, signatures of the magnetic field of the black hole are layered on top of the original glowing ring, revealing a smooth, organized pattern that wraps around the auxiliary object. Moscibrodzka and her colleagues studied charged particles that detect magnetic field lines to give a more detailed look at the extreme physical conditions around the black hole.
Color in a place that never leaves
Now, as reported in the new study, observations with more wavelengths further color the palatable image.
Scientists hope that these combined observations will help to reveal the physics that the giant particle particles erupt from the core of the M87. The ray spans thousands of light-years, extending across the galaxy, and is somehow launched from the pool of blowing plasma, twisted magnetic fields and other material orbiting the black hole.
Scientists suspect that such jets may be responsible for a population of extremely high-energy cosmic particles entering our neighborhood, where cosmic rays are known. Although the sun blows a protective bubble around a large part of the solar system, energetic particles can still slip through, and some of those that descend into the Earth’s atmosphere move at such a high velocity that it cannot from the Milky Way. does not arise.
“One of the most important questions we’re trying to investigate is where the high-energy particles come from,” Markoff says. ‘How are these jets launched, what’s in them, and how are high – energy cosmic rays – apparently derived from black hole rays – accelerated? You can not answer these questions with EHT alone. ”
With the new observations, scientists can better understand the ray – which radiates light at every wavelength – from radio waves to gamma rays – and see if it throws matter into space at a velocity that the Earth’s largest particle accelerators could never equal. not. .
A better picture of the radiator’s anatomy may also reveal mysterious features of M87’s black hole, such as how fast it rotates and in what orientation. These measurements provide clues as to how the supermassive black hole has grown, and whether it has gained mass over the past billion years primarily through collisions with other supermassive black holes, or by fuming with surrounding gas.
“In a sense, the turn has a better memory of how black holes grow in mass than the mass actually measured,” says Volonteri.
On the horizon of the EHT
As this week’s observation campaign unfolds, scientists are again aiming their telescopes at M87 to see how this could change. The black hole was in a tranquil, dormant state during the 2017 observation campaign, which allowed the team to see to its core. Now, “we are very curious to see how M87 will develop on longer time scales – we are curious about what we are going to get this time around,” says Moscibrodzka.
The EHT team also peeks at the supermassive black hole closest to home: Sagittarius A *, or SgrA *, which stands in the heart of the Milky Way. With a mass equal to about four million suns, SgrA * is less solid than the bruise in M87, but it is also much, much closer to Earth and the EHT, at only 25,600 light-years away.
However, our residents’ supermassive black hole is also more temperamental. It bends and flares frequently as it devours material, and sometimes in the course of a single eruption. These fluctuations in activity are one of the reasons why it took longer to put together an image.
“From an observational perspective, it presents a lot of challenges,” Haggard said. “How do you create a stable image of something that is constantly changing?”
It’s a difficult challenge, but an image of SgrA * is imminent – and soon, with heaps of observations in hand, we will be many steps closer to understanding the tyrannical enigmas lurking in the hearts of galaxies, and some of the most extreme phenomena in the observable universe.