Astronomers are going for the first time see the eyes of the black hole event horizon
Since their very first mention of John Michell in a letter to the Royal Society in 1783, black holes do not cease to amaze the imagination of not only scientists, but also writers, filmmakers, and other creative professionals. Perhaps this interest is partly due to the fact that these mysterious objects are in fact no one has ever "seen." However, very soon things can change, as an international team of astronomers is currently completing the process of networking of several ground-based telescopes, hoping to make the first-ever picture of a black hole.
Black holes have a tremendous level of gravitational forces. Whether it is a lost star or planet - nothing can escape his fate of being completely absorbed in these astrophysical objects. Even light. After Michell existence of black holes mathematical method in 1915 - as a solution to the equations set forth in the general theory of relativity, Albert Einstein, - he predicted the German astronomer and physicist Karl Schwarzschild.
After that astronomers dismantled indirect evidence of the existence of supermassive black holes, millions or billions of times having greater mass than our Sun, and lying at the heart of all large galaxies. One of these was the effect of the indirect evidence of gravitational ties, which turned out to nearby stars, wrapped around the galactic center. When glut surrounding galactic matter, black holes emit powerful plasma jets at speeds often approaching the speed of light. This is yet another evidence of their existence. Last year, as part of an experiment LIGO scientists were able to produce more evidence of their existence, by determining the so-called gravitational waves - ripples of space-time caused by the two black holes in the middle of mass, confronted each other several million years ago.
And yet, despite the fact that we know of their existence, questions the nature of black holes and their evolution and impact on the universe still remain open, even for modern astronomy, whose technology has advanced as compared with the time when a black holes just started talking.
Catching a tiny spot in the sky
From 5 to 14 April 2017 the team behind the mission of the telescope Event Horizon Telescope (EHT), hopes to test fundamental theories about the physics of black holes and try to make the first-ever image of the event horizon of a black hole (a so-called point of no return, according to the same theories ).
The EHT based on the so-called technique of interferometry with a long base (Very Long Baseline Interferometry, VLBI), allowing to combine a plurality of the global network of terrestrial telescopes, thus creating a giant telescope size of the Earth. The power of such a system should be enough to look into the heart of the Milky Way and see the black hole Sagittarius A * ( "Sagittarius A *"), which has a mass 4 million times the mass of our sun.
Black Hole "Sagittarius A *" - the main purpose of this study The presence of this black hole astronomers hints disk of gas and dust, wrapping around her. The gravitational field of the object distorts the light passing through the disk matter. According to astronomers, the color and brightness will also vary in a predictable manner.
Under the direct supervision of a black hole with the help of Event Horizon Telescope, astronomers hope to see an object in the shape of a crescent, rather than in the form of a full disk. It is quite possible, even be able to see the shadow of the event horizon of a black hole against the bright and sparkling material in her side of the gas cloud.
Sheer Event Horizon telescope network consists of nine stations - are presented some separate telescopes, some are immediately set of multiple telescopes - located in Antarctica, Chile, Hawaii, Spain, Mexico, and USA (Arizona). The development of a "virtual" telescope was carried out for many years. To a large extent this was due to test new technologies. However, initial tests have shown limited sensitivity and lack of resolution, not allowing to achieve the desired result to be able to observe the black hole. Adding to the network more sensitive telescopes, including the Atacama Large Millimeter Grid (ALMA), located in Chile, as well as the South Pole Telescope, it has allowed to add the necessary power the virtual system. The effect was almost the same as when equipped points where, instead of vague bright spot you see two headlights of the approaching car to you. By itself, a black hole in the background space is a very compact object for observation. See its presence in the optical spectral range (when you can own eyes to see the light) is quite impossible, because the waves are blocked by a huge accumulation of dust and gas located around the black hole. However, the telescopes with the desired resolution, and working in a long, millimeter wavelengths, are able to break through the cosmic fog.
The resolution of the telescopes of any kind - the finest characteristics, which can be adjusted and measured - usually expressed in terms of angular resolution, ie the ability of the optical system to distinguish the points represent the surface. Measured in seconds of arc (arcseconds) and minutes (arcminutes) as well as degrees. For example, the angular size of the moon relative to the Earth is half a degree or take 1800 arcseconds of our sky. For any telescope more aperture (diameter), the finer details of the system is able to see on the observed object.
Resolution single telescope (usually from 100 m aperture) is about 60 arcsec. This compares with the naked eye resolution looking at 1/16 the diameter of the full Moon. By combining a plurality of telescopes Event Horizon Telescope system can achieve resolution of 15-20 mikroarksekund (0 arcsec 000015), which is equivalent grape, distinguishable on a distance from the earth to the lunar surface.
What's at stake?
Despite the fact that the practice of combining several telescopes into a single network has already been applied, specifically in this case, towards the creation of Event Horizon Telescope contains many difficulties and pitfalls.
The data to be recorded by each station, which is part of the overall network will be sent to a central computerized center, where the supercomputer will accurately process them and integrate. The difference in weather conditions, atmospheric conditions, the state of the telescopes themselves in each individual case will be significantly different and require very fine calibration to scientists were able to obtain a final image of an object with a minimum (or even better - a complete lack of) artefacts.
If researchers succeed and will finally get the first real images of the event horizon of a black hole, it will open up a whole new era in the study of astrophysical objects and will solve a lot of interesting puzzles, one of which reads as follows: if there is a general, this event horizon?
Does Einstein's theory in the conditions of such a powerful gravitational or do we need to develop other theories of gravity in respect of black holes? How to feed the black holes and how much material is then emitted in the form of jets? All these questions need to be answered so far.