After a long exploration of black holes, astronomers at more than 30 institutes around the world completed their work on black holes in April 2017. In April 2019, the first black hole photos were released, a milestone in black hole research. A year later, astronomers released the world’s second black hole , a 5.5 billion light-year-old image of the quasar 3C 279 central core and the origin of its jet stream, taken in April 2017.
The results of the study, published in the journal Astronomy and Astrophysics, on 7 April 2020, are published in the journal Event Horizon Telescope imaging of the archetypal blazar 3C 2C 279 at at an extreme 20arc microsecond Resolution (20 microsecond extreme resolution imaging of quasars 3C279 by the Event Vision Telescope), co-authored hundreds of people.
Mysterious celestial bodies
Everyone must have heard of the black hole.
In 1915, Einstein completed the foundation of his general theory of relativity, which was officially published the following year. General relativity predicts the existence of an object in space that is caused by gravitational collapse struck by a star of a mass large enough to die after the fuel for the nuclear fusion reaction runs out. The object is extremely dense and extremely small, and has a gravity that is so strong that even light is attracted to escape.
In 1916, the German physicist Karl Schwarzschild made an accurate solution to this prediction , which calculated a vacuum solution to Einstein’s field equation, which showed that if the actual radius of a static sphere symmetrical star was less than a fixed value (which is the famous Swasi radius), a strange phenomenon would occur around it: once it entered an interface known as the “view”, even light could not escape.
It was not until 1969 that American astrophysicist John Archibald Wheeler first came up with the concept of a “black hole” that spread the world.
In 1970, the U.S. satellite Liberty discovered the X-1, a different constellation of cygniats than other ray sources, with a giant blue planet more than 30 times heavier than the sun, which is towed by an invisible object as heavy as 10 suns. Astronomers agreed at the time that the object was a black hole, the first black hole ever discovered by man.
In general, scientists have a difficult path to black holes, in large part because they cannot be directly observed, so scientists can only learn indirectly about their existence, mass, and their effects on other things.
Before an object is inhaled by a black hole, the acceleration caused by the black hole’s gravity causes friction, which in turn releases “edge messages” of x-rays and gamma rays, and this is the evidence scientists have obtained for the existence of black holes. Of course, by indirectly observing the orbits of stars or interstellar cloud clusters, scientists can also find some clues.
Take a picture of an invisible black hole
To learn more about black holes and the universe, scientists have used a tool, radio telescopes.
Radio telescopes refer to the basic equipment for observing and studying radio waves from celestial bodies, including directional antennas that collect radio waves, highly sensitive receivers that amplify radio signals, information recording, processing and display systems, etc., to measure the intensity, spectrum and polarization of celestial radio.
For the study of black holes, the scientists used a network of multiple radio telescopes called the Event Horizon Telescope ( EHT). It is not difficult to see by name that what it is trying to observe is in fact the “event horizon” of a black hole.
As mentioned above, we can interpret the event horizon as a space-time boundary. In the event horizon around the black hole, under the influence of very large gravitational force, the escape speed near the black hole is greater than the speed of light, making it impossible for any light to escape from the event horizon, and the event horizon will not be affected by the black hole.
In 2006, scientists at more than 30 institutes around the world teamed up to launch an ambitious plan to take pictures of black holes.
Specifically, the program is based on very long baseline interference (VLBI), which combines eight radio telescopes in various parts of the world to observe the same target source and record data, resulting in a virtual telescope with a diameter equivalent to the Earth’s diameter, increasing the angular resolution of the telescope to a level sufficient to observe the visual scale structure of events.
It is worth noting that not all of the eight radio telescopes mentioned above are single telescopes, including telescope arrays, such as the Atacama large millimeter array in Chile, which consists of more than 70 small telescopes.
In April 2017, humans completed the long process of data processing after taking pictures of black holes.
In September 2019, the Event Vision Telescope Collaboration won the 2020 Academy Of Sciences Science Breakthrough Award for Basic Physics.
Finally, on April 10, 2019, at 9:00 EST (10:00 BST), simultaneous press conferences were held in Washington, D.C., Shanghai and Taipei, Santiago, Chile, Brussels, Denmark, and Tokyo, Japan, to reveal the first major achievement of the Event Vision Telescope, the first black hole ever obtained.
The world’s second black hole photo
Although the second black hole photo is as tall as the first, it is significant for the study of quasars.
Quasar, in fact short for a star-like object, is the nucleus of a galaxy that is the furthest and most energetic from Earth, much smaller than a galaxy, but emits more than a thousand times the energy of a galaxy.
Quasars and pulsars, microwave background radiation, and interstellar organic molecules were once known as the “four discoveries” of astronomy in the 1960s. Astronomers have long puzzled.
It is understood that 3C 279 is an optical lysator, after scientists first detected the super-speed motion of quasars is detected on the star.
In fact, astronomers chose 3C279 as their observations for two possible reasons:
Unlike other quasars, the supermassive black hole at the center of 3C279 is surrounded by a gas accretion disk that emits strong radiation (Note: a mixture of gas and dust that surrounds the star), making it easier to observe;
Researchers discovered years ago that the black hole had a weaker gamma-ray emitter.
In April 2017, researchers used ultra-high angular resolution technology — a 1.3mm (230GHz) very long baseline interference technique — to distinguish the 3C279’s central jet stream to study its fine scale pattern of proximity to the jet stream emitter, where the highly variable gamma rays originate.
It’s worth noting that the black hole in this image is completely different from the virtual, hypothetical — astronomers agree that the black hole’s radiation jet stream is linear, but this photo reveals for the first time that the jet stream is curved. Although the rationale is not yet known, the discovery will undoubtedly help scientists better understand the physical properties around black holes.
In addition, the researchers noted that the rotating material on the accretion disk caused subtle changes when it dropped the black hole, something that had never been seen before.