4 Feb 2020

First Image of Black Hole Captured by Scientists with the Help of Event Horizon Telescope (EHT Telescope)

A black hole is a region of space-time having gravitational pull so strong that even light cannot escape from it. Because of this reason it was previously thought that it is not possible to see the black hole and capture its image.
But a team of International astronomers has made it possible. The scientists have obtained the first image of a black hole, with the help of Event Horizon Telescope.
So the question is, how it became possible to capture the black hole's image, if it does not allow even light to escape.

First Image of Black Hole Captured Video



 

Actually scientists did not take photograph of the black hole directly. They captured an image of the hot glowing gas falling into the black hole.
But the major problem they were facing was the Great distance of the black hole. Actually it is very difficult to capture the image of the objects that are very far away from us as they appear small and dim from Earth. So a telescope with very large aperture is required to gather as much light as possible for high resolution image.

Event Horizon Telescope (EHT Telescope)

So the scientists created a network of telescopes known as the Event Horizon Telescope (EHT). This network of telescopes acts as a giant virtual telescope. The Event Horizon telescope used for this purpose had the virtual aperture equal to the diameter of earth. Two telescope stations farthest apart are present at the South Pole and in Spain. All the telescopes present in the network of the telescopes focus on the same target. Here, the target object is the black hole. Resolution of the image obtained by the event Horizon telescope increases, as the number of telescopes are increased in the array.
Event Horizon telescope team decided to take images of two black holes. The first Black hole was the closest supermassive black hole present at the centre of our galaxy Milky Way. Name of this supermassive black hole is sagittarius A*. it is present at a distance of 26,000 light years from us.
The second target black hole was the supermassive black hole M87*. This is one of the largest known supermassive black hole in our universe. The black hole M87 is located at the centre of the gargantuan elliptical Galaxy Messier 87, or M87 in short. This is located at a distance of 53 million light years away from the Earth.
Second black hole M87* is much more massive in comparison to the black hole present at the centre of the Milky Way, sagittarius A*. Mass of sagittarius A* is equivalent to 4 million solar masses while the M 87* black hole contains 6.5 billion solar masses.
Here you should know that one solar mass is equal to nearly 2x10^30 kgs, which is equivalent to the mass of our Sun.
Although we had a black hole, present at the centre of our own Galaxy, But still scientists selected a black hole, which is present so far away from us, why?
There are two main reasons behind this, the first reason is, the black hole M87* is substantially much more massive and larger than the one present at the centre of the milky way which obviously makes it a better candidate for capturing its image.
The second reason is, unlike Sagittarius A*, it is an active black hole. Being an active black hole means, it eats lots of material present in its surroundings.
But still, it is really a big challenge to capture the image of a target present at such a great distance.
The level of difficulty of this task can be understood by a statement made by Katie Bouman, a computer scientist in this project, according to him, "It's akin to capturing an image of an orange on the surface of the Moon."
Each telescope used for the event Horizon telescope had to be highly synchronized with the others. It is because of the high degree of precision of the EHT which makes it possible to resolve objects 4,000 times better than even the Hubble Space Telescope.
But why scientists are trying so hard and investing so much money on the project just to capture the image of a black hole. Why it is so important? As we know, black holes can not be seen directly as they do not allow the light to escape from it. It is the very first time, that we have captured the image of the black hole. It will reveal various mysteries of the universe. Out of these the most important and interesting is the general theory of relativity by Einstein. The general theory of relativity has been proved accurate for smaller mass objects like earth and average sized stars similar to our Sun. But the theory has not yet been directly proven for other regions containing extremely high  dense matter like black holes.
With the help of Image obtained of the black hole, the calculation of the mass of the black hole can be done directly.
When the scientists measured the radius and mass of the black hole M87* directly using the image obtained, it was very close to the one derived from a method used indirectly for this purpose that uses the motion of orbiting stars.

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