In the heart of a gigantic galaxy 55 million light-years away, a black hole 6.5 billion suns high throws a fountain of matter into space at almost the speed of light. Using a matrix called the Event Horizon Telescope (EHT), scientists harnessed radio waves to capture a cup of that black hole, giving our first glimpse of the environment extremely close to its edge in 2019.
Two years later, the international team that provided the stunning image, along with additional partners, published the results of a 2017 observation campaign that simultaneously examined the host galaxy, Messier 87, at multiple wavelengths.
The report, which appears today in The astrophysics journal, includes data from 19 observatories based on Earth and space and is written by over 750 scientists. It describes a more complete view of the supermassive black hole and its massive jet, allowing scientists to take a good look at how magnetic fields, particles, gravity and radiation interact in the vicinity of a supermassive black hole on multiple scales.
“This is the kitchen sink of physics, isn’t it?” It’s all there, ”says Daryl Haggard of McGill University, who helped coordinate observations with multiple wavelengths. “We’re really starting to see orbits, see right next to the black hole and explore this exotic environment.”
“I think this is one of the newspapers that really connects EHT to the rest of the community – it’s an idea of what the installation really intends to do,” added team member Sera Markoff of the University of Amsterdam. “I feel like this is the beginning of it all.”
Now, the EHT team is in the middle of a crucial 12-day observation period – the first they have been able to do since 2018, due to technical issues and the coronavirus pandemic. This time, the collaboration has added three new telescopes to its successor to observatories, including a Greenland installation, and is again scanning the sky in wavelengths that span the electromagnetic spectrum – as long as the weather cooperates.
“You have to have great weather everywhere,” says Monika Moscibrodzka of Radboud University. “And the more sites you have, the lower the probability of good weather on each of them.”
A cosmic cruller
Black holes have been among the most interesting and compelling astronomical phenomena for more than a century, surprising our imagination with their extreme physics and the fact that what enters never returns. But these cosmic sinkholes have only recently been concentrated, thanks to the EHT image, as well as Nobel Prize-winning studies of objects revolving around the supermassive black hole in the heart of the Milky Way, and a wealth of information gathered from the black hole. they.
“In recent years, we have gone from black holes as science fiction to black holes as reality,” says Marta Volonteri of the Institut d’Astrofizica in Paris.
The Event Horizon telescope actually includes several radio telescopes scattered around the globe, from Greenland to the South Pole, which together act as an Earth-sized observer. Making these images with the M87’s supermassive black hole requires the combination of an enormous amount of data – so much data that the team can’t transfer them digitally and instead has to throw their hard drives in the mail.
When the team released its first image in April 2019, scientists were amazed because the object looked almost exactly as predicted by a century-old theory.
M87’s image provided an opportunity to test Einstein’s theory of general relativity in 1915, which argues that what we perceive as gravity occurs when matter curves space-time fabric. The environment around the heart of the M87 is intense – a hot mess of extreme gravity, magnetic fields and particles – which makes it one of the best places in the universe to challenge general relativity.
“Everyone is always trying to break these theories, because we learn so much when we find a pinch in armor,” says Haggard. “We like to break patterns. But we have not yet successfully broken general relativity. ”
While general relativity prevailed again with M87, the EHT image quickly ignited public awareness. The XKCD smart comic presented the team several times and superimposed the solar system over the jaw of the black hole to show its magnitude. Others compared his shiny ring to Sauron’s eye from Lord of the Rings movies. But the most energetic debate erupted over the resemblance to breakfast food.
“Is it more like a pretzel or a donut?” Volunteers ask.
An update of that original image, assembled by Moscibrodzka and her colleagues, solved the argument last month: the black hole looks like a cruller or a fluted donut. In the newer image, the signatures of the black hole’s magnetic field are layered over the original shiny ring, revealing a smooth, organized pattern that wraps around the awful object. Moscibrodzka and her colleagues studied the charged particles that trace the lines of the magnetic field to provide a more detailed look at the extreme physical conditions surrounding the black hole.
Colored in a place that the light never leaves
Now, as reported in the new study, the wavelength observations still color the tasty image.
The scientists hope that these combined observations will help reveal the physics that fuel the mammoth jet of particles erupting from the core of M87. The jet spans thousands of light-years, spanning the galaxy, and is somehow released from the vesicle plasma pool, twisted magnetic fields, and other matter that revolves around the black hole.
Scientists suspect that such jets could be responsible for a population of extremely high-energy cosmic particles heading towards our neighborhood, where they are known as cosmic rays. Although the sun blows a protective bubble around a large part of the solar system, the energy particles can still slide and some of those that hit the Earth’s atmosphere travel at such huge speeds that they cannot originate from the Milky Way.
“One of the main questions we’re trying to investigate is where the high-energy particles come from,” says Markoff. “How are these jets launched, what is in them and how are the cosmic rays of high energy accelerated – which seem to come from the jets of black holes? You cannot answer these questions with EHT alone. ”
With the new observations, scientists can better understand the jet – which emits light at every wavelength, from radio waves to gamma rays – and see if it is, in fact, throwing matter into space at a speed that most Earth’s great particle accelerators could never match it. .
Also, a better picture of the jet’s anatomy could reveal some still mysterious properties about the M87’s black hole, such as how fast it rotates and in what direction. These measurements will provide clues as to how the supermassive black hole grew and whether it has gained mass in the last billion years, mainly from collisions with other supermassive black holes or from the surrounding gas festival.
“In a sense, rotation has a better memory of how black holes grow in mass than the actual measurement of mass,” says Volonteri.
On the EHT horizon
As this week’s observation campaign unfolds, scientists are once again pointing their telescopes at the M87 to see how it could have changed. The black hole was at rest and sleepy during the 2017 observation campaign, which let the team see right into its core. Now, “we are very curious to see how M87 will evolve over longer periods of time – we are curious about what we will achieve this time,” says Moscibrodzka.
The EHT team also takes a look at the supermassive black hole closest to the house: Sagittarius A * or SgrA *, which is parked in the heart of the Milky Way. With a mass equal to about four million suns, SgrA * is less powerful than bruises in the M87, but it is also much, much closer to Earth and EHT, just 25,600 light-years away.
However, our resident’s supermassive black hole is also more temperamental. It frequently belches and ignites while freezing material, sometimes having outbursts over a single evening. These fluctuations in activity are one of the reasons why it takes more time to put an image together.
“From an observational perspective, it introduces a lot of challenges,” says Haggard. “How do you make a stable image of something that varies all the time?”
It’s a difficult challenge, but an image of SgrA * is on the horizon – and soon, with a bunch of observations in hand, we’ll be many steps closer to understanding the riddles hiding in the hearts of galaxies and creating some of them. the most extreme phenomena in the observable universe.