It is the first direct observation to confirm the existence of a black hole known as Sagittarius A * as the pulsating heart of the Milky Way.
The black holes do not emit light, but the shadow of the black hole is surrounded by a glowing ring in the image, the light is bent by the gravity of the black hole. Astronomers have said that the black hole is four million times larger than our sun.
Michael Johnson, Astrophysicist, Astrophysics: “For decades, astronomers have wondered what is at the core of our galaxy, which pulls stars into tight orbits with tremendous gravity” | In the statement of Harvard and Smithsonian.
“With the help of the image (Event Horizon Telescope, or EHT), we zoom in a thousand times closer to these orbits, where gravity increases a million times. At this distance, the black hole accelerates matter to approach the speed of light and bends the photon orbits into twisted (space-time) paths. “
The black hole is about 27,000 light-years from Earth. Our solar system is located in one of the spiral arms of the Milky Way, which is why we are so far from the galactic center. If we could see this in the night sky, the black hole would appear to be the same size as a donut sitting on the moon.
“We were surprised at how well the ring size met the expectations of Einstein’s general theory of relativity,” said Jeffrey Bauer, an EHT project researcher at the Academia Sinica Institute of Astronomy and Astrophysics in Taipei.
“These unprecedented observations have greatly improved our understanding of what is happening in our galaxy (in the center) and provide new insights into how these giant black holes interact with their environment.”
Looking for a black hole
It took the astronomers five years to capture and confirm this image and discovery. Earlier, scientists found stars orbiting some huge invisible objects in the center of the galaxy.
Ramesh Narayan, a theoretical astrophysicist at the Center for Astrophysics: “Now we see a black hole swallowing gas and light nearby and pulling them into a bottomless crater” | In the statement of Harvard and Smithsonian. “This picture confirms decades of theoretical work to understand how black holes wear out.”
This discovery was made possible by more than 300 scientists from 80 facilities working with a network of eight different radio telescopes around the world that make up the Event Horizon.
The telescope is named after the “event horizon” where light cannot escape from the black hole. This global telescopic network essentially forms one virtual “Earth-sized” telescope when all eight are interconnected and the observations are side by side.
Although both images are similar, the A * arc is more than 1000 times smaller than the M87 *.
“We have two completely different types of galaxies and two very different masses of black holes, but near the edge of these black holes they look remarkably similar,” said Sera Markov, chairman of the EHT Scientific Council and professor of theoretical astrophysics. institute. University of Amsterdam in its statement.
“This tells us that (Einstein’s general theory of relativity) controls these things closely, and all the differences we see further away are due to differences in the matter surrounding black holes.”
Unable to take photo
Although the black hole in the Milky Way is closer to Earth, it was difficult to describe.
“The gas near the black holes is moving at the same speed – at about the same speed of light – around Sgr A * and M87 *,” EHT researcher Chi-Kwan of the Chan Steward Observatory and the University’s Department of Astronomy and Science, Arizona, said in a statement.
“But when a gas takes days or weeks to orbit a larger M87 *, at a much smaller Sgr A * it orbits in a few minutes. This means that the glow and pattern of the gas around Sgr A * changed rapidly during the observation of the EHT co-operation – little like an attempt would be made to take a clear picture of a puppy chasing him quickly. ”
The global network of astronomers had to develop new tools to enable the rapid movement of gas around Sagittarius A *. The resulting image is the average of the images taken by the group. According to Caltech researchers, taking a picture of Sagittarius A * was like photographing a grain of salt in New York with a camera in Los Angeles.
“This Event Horizon telescope requires more than just taking a picture from a telescope in the high mountains. It is the product of technically challenging telescope observations and innovative computational algorithms,”
Each telescope is pushed to its maximum limit, called the diffraction limit, or the maximum number of features it can see per minute.
“And that’s basically the level we see here,” Johnson said at a news conference. “It’s not clear why we need to move the telescopes away or move to higher frequencies to make the picture clearer.”
By describing two completely different black holes, astronomers can determine their similarities and differences and better understand how gas behaves around supermassive black holes, which can contribute to the formation and evolution of galaxies. Black holes are believed to be in the middle of most galaxies and act as their engines.
At the same time, the EHT team is working to expand the telescope network and make updates that could lead to more impressive images and even movies of black holes in the future.
Capturing a moving black hole can show how it changes over time and what the gas does as it circulates the black hole. Bowman and EHT member Antonio Fuentes, who joins Caltech as a postdoctoral researcher in October, are developing methods to link images of black holes to reflect this movement.
This “first live image of the gentle giant in the center of our galaxy” is just the beginning, said Ferial Ozil, a member of the EHT Science Council and professor of astronomy and physics, and dean of research at the University of Arizona. Press conference.
“This image is a testament to what we can achieve as we bring together our brightest minds as a global research community to make the seemingly impossible and possible of the National Science Foundation, Sithuraman Panchanathan, in a statement. “Language, Continents and even the galaxy cannot stop what humanity can achieve when we unite for the common good.”