With the addition of a new telescope to the most southerly point on Earth, the Event Horizon Telescope project (EHT), which currently covers the diameter of our planet, will be able to help an astronomer capture a bright ring surrounding a supermassive black hole.
Using a method known as an ultra-long-base interferometer, astronomers can combine telescope observations located in remote locations around the planet. The distance between these observatories, known as the “baseline,” simulates a virtual telescope of the same diameter. Thus, if you have telescopes scattered across the hemisphere of the globe at a distance of 5,000 miles, you essentially imitate a giant telescope with a diameter of 5,000 miles.
Of course, this is not an easy task to build a bunch of telescopes and send them to a celestial object in the hope of getting any data, but as equipment communications technology and computing software becomes more sophisticated, ambitious projects such as EHT are becoming increasingly popular.
Now scientists are trying to make direct observations of a supermassive black hole in the center of our galaxy, located in a powerful radio source called Sagittarius A. For this, the South Pole Telescope (SPT), located at the Amundsen-Scott polar station, joined the EHT and opened the era of studying the most extreme objects of our universe.
The South Pole telescope is a 10-meter telescope that is sensitive to millimeter-wavelengths and will be used to create a high-resolution image of a cosmic microwave background radiation or relic radiation. Associated with the Event Horizon Telescope project, this telescope has a unique location and will give a tremendous impetus to the development of a super-long-base interferometer project.
The South Pole telescope and the Atacama Pathfinder Experiment radio telescope were first combined in an interferometer project with a super-long base in January. Two sources can simultaneously observe two sources: a black hole located in the center of the Milky Way galaxy, Sagittarius A * and a black hole located in the center of a distant galaxy Centaurus A.
“Now that we’ve connected an extra-long-base interferometer to SPT, the Event Horizon Telescope project really covers the entire Earth, from a sub-millimeter telescope on Mount Graham in Arizona, California to Hawaii, Chile, Mexico, Spain and the South Pole,” said Dan Marroun. from the University of Arizona. “Connecting SPT gives us significantly greater resolution than resolution of our past arrays, which is crucial for EHT purposes. To make sure the event horizon exists around the black hole and test Einstein’s theory of general relativity, we must make a detailed picture of the black hole. Thanks to EHT we are able to do this. "
We predict that when the EHT project is launched, it will be 1000 times more powerful than the Hubble Space Telescope, and we will be able to see a bright ring or crescent surrounding a supermassive black hole in the core of the Milky Way. Although a supermassive black hole is 4,000,000 times more massive than our Sun and located at a distance of 26,000 light years, its predicted size will be relatively tiny.
"Since the size of the event horizon will be less than the orbit of Mercury around the Sun, but it will be located at a distance of 26,000 light years from Earth, studying the event horizon will be like reading a newspaper in New York while standing in California," University of Arizona release However, astrophysicists are worried about what we will see.
If our current understanding of how a black hole works is true, then we have a general idea of what we will see. Although the event horizon is the point of no return, even for light, the extreme physics of a black hole generates powerful radiation. In this case, the EHT will have to imprint a partial or complete ring structure. The energy radiation that shines around a very specific dark shadow is the shadow of the event horizon.
A simulation of how a black hole might look like when using an EHT. Left: modeling the black hole event horizon. In the center: how this ring can look from an array of 7 telescopes. Right: how the ring will look from an array of 13 telescopes. The resolution of the EHT increases with the number of telescopes.
“We are very pleased that SPT has become part of the EHT,” said John Karlstrom, who collaborates with SPT. "It will be so interesting to look back at the beginning of the universe." "I have been observing this project with great interest for several years and it is good to see that EHT takes on a certain shape."