Event Horizon Telescope captures image of supermassive black hole at center of Milky Way

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Astronomers on Thursday unveiled the first image of a supermassive black hole that’s rattling the center of our galaxy, its gravity so powerful it bends space and time and forms a glowing ring of light with eternal darkness at its core.

The black hole, seen from Earth near the constellation Sagittarius, has a mass equal to more than 4 million suns. The new image shows it with three bright spots along a ring that, to the scientists’ surprise, tilts face-on toward Earth.

By the standards of other supermassive black holes, the scientists said, the one at our Milky Way’s core is relatively quiet — as quiet as something that engulfs stars and reaches temperatures measured in the trillions of degrees.

University of Arizona astronomer Feryal Ozel described the realization as “the first direct image of the gentle giant at the center of our galaxy”.

“We find a bright ring surrounding the shadow of the black hole,” she said. “It seems that black holes like donuts.”

The image was captured by a worldwide consortium of astronomical observatories, known as the Event Horizon Telescope. Three years ago, the project produced the first image of a black hole, in the galaxy Messier 87.

The black hole at the center of the Milky Way is more than a thousand times smaller than that of Messier 87. But cosmically speaking, it is the closest to home. The unveiling of the image at the National Press Club in Washington was part of simultaneous media events on several continents. The image was kept under wraps pending unveiling at 9:07 a.m. sharp EST.

The achievement, supported by the National Science Foundation, drew on contributions from more than 300 scientists from 80 institutions, including eight telescopes. The data collected required years of processing and analysis. The black hole itself is not static but changes appearance on short timescales, challenging scientists to produce a singular image that matches what their telescopes had observed. And the pandemic has added its own challenges.

“The pandemic slowed us down but it couldn’t stop us,” MIT Haystack Observatory researcher Vincent Fish said at the press conference.

Discover a black hole for the first time in a historic image from the Event Horizon Telescope

The work turned out to be exciting in the end.

“What’s cooler than seeing the black hole at the center of our Milky Way?” said team member Katherine Bouman, a computational imaging scientist at Caltech.

“These are the most mysterious objects in the universe, and they hold the keys to large-scale structure in the observable cosmos,” said Sheperd Doeleman, an astronomer at the Harvard-Smithsonian Center for Astrophysics and founding director of the Event Horizon Telescope. , in an interview ahead of Thursday’s briefing.

The Milky Way’s central black hole has so far been inferred from its effect on nearby stars and dust, rather than directly observed. It is very far away – about 27,000 light-years away – and despite its “supermassive” designation, isn’t very big in the grand scheme of things, which makes direct observation with telescopes extremely difficult.

This challenge led to the creation of the Event Horizon Telescope, which is not one telescope but a group of them. The project uses an observation technique known as very long baseline interferometry, which requires careful calibration to allow multiple radio dishes spread across the planet to operate as if they were a single instrument of the size of the Earth. The consortium claims that this technique enables resolution of distant objects that would be equivalent to being able to spot a ping-pong ball on the moon.

Black holes come in two scales: “stellar mass,” which forms when stars collapse, and “supermassive,” monsters that can weigh millions or even billions of times larger than our sun and which are what the Event Horizon telescope is designed to detect.

“The black hole attracts a lot of gas towards it. Its gravitational pull is so strong that the matter around it cannot resist. But that pulls it into an extremely small space,” Doeleman said. “Imagine sucking an elephant through a straw.”

A brief history of black holes while we wait for the big reveal from the Event Horizon Telescope

The event horizon of a black hole is the boundary of no return – the point at which a falling piece of matter disappears into an inescapable gravity well. As bizarre and mysterious as a black hole can be, Earthlings should understand that it poses no threat to our world and is essentially just part of the galactic furniture.

Albert Einstein’s 1915 theory of general relativity postulated that gravity is the result of massive objects bending the fabric of spacetime. As theorists uncovered the implications of Einstein’s equations, they realized that an object with sufficient mass would create a gravity well so severe that not even light could escape.

The idea of ​​such black holes remained largely in the theoretical realm until the late 20th century. Gravitational waves from colliding black holes were discovered in 2016.

Decades ago, astronomers realized that there was something at the heart of the Milky Way galaxy emitting massive amounts of radiation. It was the brightest object near the constellation Sagittarius. Was it produced by a black hole? It has become the consensus. The bright astronomical object became known as Sagittarius A*.

Astrophysicists Andrea Ghez and Reinhard Genzel received the 2020 Nobel Prize in Physics for discovering that stars in the galactic center of the Milky Way move in a pattern consistent with orbits around a supermassive black hole.

Astrophysicists believe black holes are common to the cores of galaxies — and are somehow intrinsic to galactic evolution — though the chicken and egg question remains unresolved. One possibility is that black holes are the seed of a galaxy. The other is that black holes form more gradually as stars fall into the galaxy’s central gravity well.

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