New black hole images contain clues to cosmic mysteries

In the heart of a giant galaxy 55 million light-years away, a black hole with the weight of 6.5 billion suns throws a source of matter into space almost at lightning speed. Using a set called the Event Horizon Telescope (EHT), scientists controlled radio waves to capture a photo of that black hole, offering our first-ever look at the extreme environment near its edge in 2019.

Two years later, the international team that delivered the stunning picture, along with additional partners, released the results of an observation campaign in 2017 that simultaneously examined the host galaxy, Messier 87, in multiple wavelengths.

The report that appears today in The Astrophysics Journal, includes data from 19 terrestrial and space observatories, and is written by more than 750 scientists. It describes a more complete view of the supermassive black hole and its massive jet, letting scientists take a good look at how magnetic fields, particles, gravity and radiation interact within a surrounding supermassive black hole on multiple scales.

“That’s the physics kitchen sink, isn’t it?” It’s all there, “says Daryl Haggard of McGill University, who helped coordinate the multi-wave observations.” We’re really starting to see orbits, we’re seeing right next to the black hole and exploring this exotic environment. “

“I think this is one of the articles that really connects EHT to the rest of the community – it’s a taste of what the facility really intends to do,” adds teammate Sera Markoff of the University of Amsterdam. “I feel like this is at the beginning of everything.”

Now the EHT team is in the midst of a crucial 12-day observational 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 to its range of observatories, including a facility in Greenland, and it again scans the sky in wavelengths that span the electromagnetic spectrum – provided the weather cooperates.

“You need very good weather everywhere,” says Monika Moscibrodzka of Radboud University. “And the more websites there are, the lower the probability of good weather at each of them.”

Cosmic crawl

Black holes have been among the most interesting, compelling astronomical phenomena for over a century, capturing our imaginations with their extreme physics and the fact that what comes in never appears again. But these cosmic dolines have only recently come into focus, thanks to the EHT image, as well as Nobel Prize-winning studies of objects surrounding the supermassive black hole at the core of the Milky Way and a lot of information gathered from looking like black. holes shatter each other.

“In recent years, we’ve gone from black holes like science fiction to real black holes,” says Marta Volonteri of the Institut d’Astrophysique in Paris.

The Event Horizontal Telescope actually consists of many radio telescopes scattered around the globe, from Greenland to the South Pole, that work together as a ground-sized observatory. Making these images of the M87’s supermassive black hole requires combining a huge amount of data – so much data that the team can’t digitally transmit it and instead has to throw 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 century-old theory.

M87’s image offered an opportunity to test Einstein’s theory of general relativity in 1915, which requires that what we perceive as gravity appear when matter curves the fabric of space-time. The environment around the heart of M87 is intense – a hot disorder 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 chin in the armor,” Haggard says. “We love breaking patterns. But we have not yet successfully broken general relativity. “

While general relativity reigned again with M87, the EHT image quickly took hold in the public consciousness. The brain comic XKCD presented the team several times, and superimposed the solar system on the jaw of the black hole to show its scale. Others have compared its shining ring with the Eye of Sauron of The Lord of the Rings movies. But the most energetic debate has erupted over its resemblance to breakfast foods.

“Does it look more like a donut or a bun?” Willingly asks.

An update to that original image, put together by Moscibrodzka and her colleagues, resolved the argument last month: the black hole looks rougher, or grooved ring bun. In the newer image, signatures from the field of the black hole are layered on the original glowing ring, revealing a smooth, organized pattern that wraps around the massive object. Moscibrodzka and her colleagues studied charged particles that track magnetic field lines to give a more detailed look at the extreme physical conditions around the black hole.

Colorado in a place that the light never leaves

Now, as reported in the new study, multi-wave observations are further colored in that delicious picture.

Scientists hope these combined observations will help uncover the physics that drive the giant jet of particles coming out of the core of M87. The jet spans thousands of light-years, stretching across the galaxy, and is somehow launched from the pool of light bulb plasma, twisted magnetic fields and other things around the black hole.

Scientists suspect that such jets could cause a population of extremely high-energy cosmic particles to go to our neighborhood, where they are called cosmic rays. Although the sun blows a protective bubble around much of the solar system, energy particles can still glide through them, and some of those that strike the Earth’s atmosphere travel at such tremendous speeds that they cannot be originated by the Milky Way. Way.

“One of the main questions we’re trying to explore is where the high-energy particles come from,” Markoff says. “How do these jets launch, what’s in them, and how do high-energy cosmic rays – which appear to be coming from black hole jets – accelerate?” You cannot answer these questions alone with EHT. “

With the new observations, scientists can better understand the jet – which emits light at all wavelengths, from radio waves to gamma rays – and see if it actually throws matter into space at a speed that the largest particle accelerators in the world. Earth could never match. .

Also a better picture of the jet’s anatomy could reveal some still mysterious features about the M87’s black hole, such as how fast it turns, and in what orientation. These measurements will provide clues as to how the supermassive black hole grew, and whether in the last billion years it has gained mass primarily from collisions with other supermassive black holes, or by feasting on surrounding gas.

“In a way, the spine has a better memory of how black holes grow in mass than actually measuring mass,” says Volonteri.

On the horizon of EHT

As this week’s observation campaign unfolds, scientists are once again aiming their telescopes at M87 to see how it may have changed. The black hole was in a quiet dormant state during the observation campaign in 2017, which let the team see right into its core. Now, “we’re very curious to see how M87 will evolve on longer time scales – we’re curious about what we’re going to get this time around,” Moscibrodzka says.

The EHT team also takes a look at the massive black hole closest to home: Sagittarius A *, or SgrA *, which is parked in the heart of the. With a mass equal to about four million suns, SgrA * is less powerful than the contusion in M87, but it is also much, much closer to Earth and the EHT, at only 25,600 light-years away.

However our resident supermassive black hole is also more temperamental. It often roars and catches fire as it swallows material, sometimes having explosions during one evening. These fluctuations in performance are one of the reasons why it takes longer to put together an image.

“From an observational perspective, that introduces a lot of challenges,” Haggard says. “How do you make a stable picture of something that is always changing?”

It’s a tough challenge, but a picture of SgrA * is on the horizon – and soon, with lots of observations in hand, we’ll be many steps closer to understanding the swirling puzzles that lurk in the hearts of galaxies, and create some of the most extreme phenomena in the observable universe.

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