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The Milky Way black hole comes to light

Astronomers announced on Thursday that they had broken through the dark and dust veil in the heart of the Milky Way galaxy and took the first photo of the “gentle giant” who lived there. Four million suns have been dispatched forever, leaving only gravity and a sharply bent space-time.

Images released at six simultaneous news conferences in Washington, DC and around the world showed a rugged donut of radio radiation framing an empty space. Oohs and aahs broke out at the National Press Club in Washington when Feryal Ozel of the University of Arizona displayed what she called “the first direct image of a calm giant in the center of the galaxy.” “It’s like a black hole like a donut,” she added.

Ozel is a collaboration of more than 300 scientists from 13 institutions operating a growing global telescope network to construct one large telescope the size of the Earth, the Event Horizon Telescope project. Is part of.

The team results were published in The Astrophysical Journal Letters on Thursday.

“I met this black hole 20 years ago, loved it, and have tried to understand it ever since,” Ozel said. “But until now, we didn’t have a direct picture.”

In 2019, the same team took an image of a black hole in the Galaxy Messier 87 or M87. The image was the first shot of a black hole and is currently enshrined at the Museum of Modern Art, New York. “We’ve seen what we thought we couldn’t see,” said Shepherd Doeleman, an astronomer at the Harvard Smithsonian Astrophysical Center at the time.

Astronomers say that the new results are gravity, galaxy evolution, and even the calm-looking star clouds like the Milky Way, our own magnificent star pinwheel, quasars, the enormous energy geysers found throughout. Said to lead to a better understanding of how to generate the cosmos.

The news also reaffirms the visionary 1971 paper by Martin Rees of the University of Cambridge and his colleague Donald Lynden-Bell, who died in 2018, and the supermassive black hole is the energy of quasars. It suggests that it was the source. Reese called the new result “logistic achievements (and I liked the computer model)” in an email.

Ozel said the resemblance of the new photo to that of 2019 indicates that the previous image wasn’t a coincidence. In an interview, Harvard physicist, historian and collaborative member Peter Galison said the M87 black hole is 1,500 times larger than the Amagawa black hole. Usually, in physics and astronomy, everything changes when something increases more than 10 times. “The similarity across such a huge scale is amazing,” Garrison said.

“This is an extraordinary test of Einstein’s general theory of relativity,” said Michael Johnson, a team member at the Harvard-Smithsonian Center, at a news event on Thursday.

Einstein’s bad dream

Black holes were an undesired result of the general theory of relativity. This is because gravity is due to the distortion of space-time due to matter and energy, causing the mattress to sag under the sleeper.

Einstein’s insights lead to a new concept of the universe that can forever disappear into the black hole mau, where space-time trembles, bends, tears, expands, swirls, and even light is so strong that it cannot escape. It was.

Einstein did not admit this idea, but the universe is now known to be spotted by black holes. Many are the remains of dead stars that have collapsed inward on their own and have just continued to advance.

However, there is a black hole in the center of almost every galaxy, including us, which can be millions or billions of times larger than our Sun. Astronomers do not yet understand how these supermassive black holes have grown.

Paradoxically, black holes are the brightest objects in the universe, despite their ability to swallow light. Matter that falls into a black hole – gas, dust, shredded stars – is heated to millions of degrees in a dense swirl of electromagnetic fields. Some of the material falls into the black hole, but some of it is ejected by enormous pressure and magnetic fields.

Such fireworks – quasars – can surpass galaxies by a factor of 1000. With their discovery in the early 1960s, physicists and astronomers took the idea of ​​a black hole seriously.

It is a mystery that created such a giant of nothingness. A wrinkle with a strong primitive energy of the Big Bang? A runaway star of a monster that collapsed and consumed its surroundings in the dawn year of the universe?

Since 1974, the center of the Milky Way has been known to coincide with a faint light source of a radio source called Sagittarius A * (pronounced Sagittarius A star). Astronomers, including Andrea Ghez of the University of California, Los Angeles and Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics, have all that has a mass of the Sun of 4.14 million and that of Mercury around the Sun. I calculated that I was trapped in a sphere of the size of an orbit. They reached that estimate by tracking the orbits of stars and gas clouds swirling around the center of the Milky Way and measuring their velocities at one-third of the speed of light. For his work, Genzel and Ghez won the Nobel Prize in Physics in 2020.

What can Sagittarius A * do other than a black hole?

Chasing the shadow

Proving that it’s a black hole was a completely different task. seeing is believing.

In 1967, physicist James Bardeen proposed to make a black hole visible to the observer as a haunted ghost in the haze of radio waves.

According to calculations made in 2000, the gravity of a black hole distorts and magnifies the image, resulting in a shadow of about 50 million miles from Earth in Sagittarius A *, as much as the orange of the moon. It looks like the size of. By Eric Agol of the University of Washington, Haino Falke of the Max Planck Institute for Radio Astronomy in Germany, and Fulvio Melia of the University of Arizona.

Since then, astronomers have sought to sharpen the acuity of the telescope and resolve its orange shadows. However, the ionized electrons and protons in the interstellar space scatter and blur the radio waves, obscuring the details of the radio source. “It’s like looking through a shower glass,” Doeleman said recently.

To see the shadows of black holes deeper, researchers needed to be able to tune the radio telescope to shorter wavelengths that could pass through the haze. And they needed a bigger telescope.

In 2009, Doeleman and his colleagues founded the Event Horizon Telescope, named after the fact that it never returned around a black hole. Currently, 11 radio telescopes are used in the joint project around the world.

The team won their first victory in April 2019, presenting a photo of the M87 black hole. In 2021, team members refined the data to reveal a magnetic field that swirls around a black hole like a finely grooved rifle barrel that sends matter and energy into a void.

Sagittarius A * data was recorded during the same observation run in 2017, which generated the M87 image, but with seven antennas because the team was able to include the South Pole Telescope, which cannot see the M87. There are no more than eight.

The Milky Way black hole is a “gentle giant” compared to the M87 black hole, where quasars shoot across space. “If our black hole was a person, Johnson said of Sagittarius A *.” The diet consists of one grain of rice every million years. “

He added that it was greedy and bright “but inefficient”. “Despite being four million times larger, it emits hundreds of times more energy than the Sun, and the only reason we can study it is because it’s in our own galaxy. is.”

Our black hole was more difficult to observe than that of M87 for another reason. With the mass and size of M87 holes less than 1/1000, our black holes evolve over 1,000 times faster, changing their appearance every 5 minutes. Ozel described it as “rumbling and rumbling.”

In contrast, the M87 black hole was barely upset during the week-long observation run, “just sitting there, like a Buddha,” Doeleman said.

“That is, in an overnight observation, it’s changing while collecting data. When I try to take a picture of something with the lens cap removed, this blurry confusion occurs.”

On Thursday, California Institute of Technology team member and computer scientist Catherine Bouman said taking a picture from the 3.5 petabytes of data from the observations was “like listening to a song playing on the piano.” “. There is no key. “

Using a technique called very long baseline interferometry, the antennas in the network were paired one by one, like an individual shaking hands with everyone in a crowd. The more telescopes you have in your network, the more you can perform such a handshake and compare the results. Computer algorithms can then start entering missing data, simulating the possible structure of a blackhole disk.

Most of these simulations, in line with the predictions from Einstein’s equations and the observations by Genzel and Ghez, portrayed a ring about the size of Mercury’s orbit.

Lia Medeiros, a team member and astrophysicist at the Institute for Advanced Study in Princeton, NJ, said:

However, not everything is perfect. Computer simulations estimated that black holes should be more noisy and more disturbing. “Something is missing,” said Priya Natarajan, an astronomer at Yale University who studies black holes and galaxy formation.

Doeleman’s next goal is to expand the network to include more antennas and get enough coverage to make a movie of the Milky Way black hole. The challenge of a black hole cinema is to depict the underlying structure of a black hole from the material moving around in the black hole.

Kip Thorne, a Nobel laureate and black hole expert at the California Institute of Technology, said he was eagerly awaiting a reliable movie of the gas flow around a black hole.

Janna Levin, a gravity theorist at Columbia University and Barnard College, who was not part of the project, agreed that the results could be spectacular and informative. “I’m not tired of black hole photos yet,” she said.


This article was originally New York Times..

https://www.ekathimerini.com/nytimes/1184296/the-milky-ways-black-hole-comes-to-light/ The Milky Way black hole comes to light

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