Photo from New Scientist.
Scientists have taken the first photo of a black hole! :D To do so, they have used a global network of telescopes. The picture shows a dark central circle, also known as "shadow", surrounded by a ring of light that is more luminous on one side.
The black hole is in the centre of a galaxy called M87. The black hole measures 40 billion km across, which means that it is bigger than our Solar System, and its mass is 6.5 billion times as big as that of our sun! How could they calculate the mass of the black hole? Well, it was thanks to the creation of the shadow, due to the gravitational bending and capture of light.
M87 is near the Virgo galaxy, which is million light-years from Earth. That means that the image of the black hole is in fact a depiction of the past, since we have to consider the immense distance that the light has to cover until it reaches the Earth.
More than 200 astronomers have been involved in this project for longer than a decade. There is so much work behind this image! The name of the telescope array, "Event Horizon Telescope", comes from that assigned to the limits of black holes, a point of no return where light cannot escape.
In order to take the picture, the power of eight radio telescopes have been combined. These telescopes are located in different places in the world, including one in the Spanish Sierra Nevada. The result has been the creation of a virtual telescope approximately as big as planet Earth.
To guarantee that the telescopes were operating simultaneously, researchers have used extremely precise atomic clocks for each of them. The telescopes have been scanning the core of the galaxy for 10 days, and have gathered 5,000 trillion bytes of information, that have been processed by supercomputers to generate the image of the black hole. Katie Bouman is the MIT student who developed an algorithm to decipher the data from the Event Horizon Telescope. I am very happy that a girl's work has been an essential contribution to this project ^_^
Moreover, we cannot overlook that Prof Falcke had the original idea for the project in 1993, when he was a Doctorate student. At the time nobody thought it was possible, but Falcke estimated there were radio emissions which could be generated close to black holes, and which would be strong enough to be captured by our telescopes.
Despite the name, black holes are not empty. They are enormous quantities of matter condensed into a much smaller area, which creates an intense gravitational field that attracts everything, even light. They also heat the surrounding dust and gas at extremely high temperatures, and distort spacetime. The material heated at billions of degrees almost reaches the speed of light. What looks like a supernatural phenomenon to me is the fact that light bends around the gravity of the black hole, creating that photon ring that we can see in the picture, or the intriguing elongated appearance that we can perceive in computer models.
One of the greatest minds in history, Albert Einstein, already predicted the visual aspect of black holes imaged two days ago.
After capturing the image of the shadow, it was compared to the computer models related to the physics of distorted space, superheated material and powerful magnetic fields. The researchers are quite satisfied because their observations match their theoretical postulations.
M87's black hole has a huge mass, and investigators think it could be the largest observable black hole from the Earth. As compared to other objects in space, black holes are relatively small, and for this reason they have not been observed before. Even though by definition they are invisible, since no light escapes from them, how black holes interact with the matter surrounding them is what reveals their appearance. The light of the halo is brighter than that of all the billion of stars in M87 combined and, according to a paper from 1973, due to their enormous gravity, black holes seem 2.5 times bigger than they actually are. These two factors have made it possible to see this black hole from our planet. Nevertheless, what we see in the photo is not the real colours of the heated gas. It is actually a colour map selected by the researchers to represent the brightness of the emissions. The most intense emission would probably look white (instead of yellow), maybe with some blue or red hues.
This is definitely a landmark to better understand the nature of these enigmatic objects. However, scientists still have to comprehend how the bright halo is generated and what happens when something falls into black holes. Although they look like simple phenomena, they raise complex questions about space and time and, ultimately, about our own existence.
Now the scientific team working in the project is imaging the black hole at the centre of our own galaxy, the Milky Way. Surprisingly, it is harder to detect than M87's black hole, which is 55 million ligh-years away. This is because the light halo around the black hole of the Milky Way is smaller and not so clear.
Sources
The black hole is in the centre of a galaxy called M87. The black hole measures 40 billion km across, which means that it is bigger than our Solar System, and its mass is 6.5 billion times as big as that of our sun! How could they calculate the mass of the black hole? Well, it was thanks to the creation of the shadow, due to the gravitational bending and capture of light.
M87 is near the Virgo galaxy, which is million light-years from Earth. That means that the image of the black hole is in fact a depiction of the past, since we have to consider the immense distance that the light has to cover until it reaches the Earth.
More than 200 astronomers have been involved in this project for longer than a decade. There is so much work behind this image! The name of the telescope array, "Event Horizon Telescope", comes from that assigned to the limits of black holes, a point of no return where light cannot escape.
In order to take the picture, the power of eight radio telescopes have been combined. These telescopes are located in different places in the world, including one in the Spanish Sierra Nevada. The result has been the creation of a virtual telescope approximately as big as planet Earth.
To guarantee that the telescopes were operating simultaneously, researchers have used extremely precise atomic clocks for each of them. The telescopes have been scanning the core of the galaxy for 10 days, and have gathered 5,000 trillion bytes of information, that have been processed by supercomputers to generate the image of the black hole. Katie Bouman is the MIT student who developed an algorithm to decipher the data from the Event Horizon Telescope. I am very happy that a girl's work has been an essential contribution to this project ^_^
Moreover, we cannot overlook that Prof Falcke had the original idea for the project in 1993, when he was a Doctorate student. At the time nobody thought it was possible, but Falcke estimated there were radio emissions which could be generated close to black holes, and which would be strong enough to be captured by our telescopes.
Despite the name, black holes are not empty. They are enormous quantities of matter condensed into a much smaller area, which creates an intense gravitational field that attracts everything, even light. They also heat the surrounding dust and gas at extremely high temperatures, and distort spacetime. The material heated at billions of degrees almost reaches the speed of light. What looks like a supernatural phenomenon to me is the fact that light bends around the gravity of the black hole, creating that photon ring that we can see in the picture, or the intriguing elongated appearance that we can perceive in computer models.
One of the greatest minds in history, Albert Einstein, already predicted the visual aspect of black holes imaged two days ago.
After capturing the image of the shadow, it was compared to the computer models related to the physics of distorted space, superheated material and powerful magnetic fields. The researchers are quite satisfied because their observations match their theoretical postulations.
M87's black hole has a huge mass, and investigators think it could be the largest observable black hole from the Earth. As compared to other objects in space, black holes are relatively small, and for this reason they have not been observed before. Even though by definition they are invisible, since no light escapes from them, how black holes interact with the matter surrounding them is what reveals their appearance. The light of the halo is brighter than that of all the billion of stars in M87 combined and, according to a paper from 1973, due to their enormous gravity, black holes seem 2.5 times bigger than they actually are. These two factors have made it possible to see this black hole from our planet. Nevertheless, what we see in the photo is not the real colours of the heated gas. It is actually a colour map selected by the researchers to represent the brightness of the emissions. The most intense emission would probably look white (instead of yellow), maybe with some blue or red hues.
This is definitely a landmark to better understand the nature of these enigmatic objects. However, scientists still have to comprehend how the bright halo is generated and what happens when something falls into black holes. Although they look like simple phenomena, they raise complex questions about space and time and, ultimately, about our own existence.
Now the scientific team working in the project is imaging the black hole at the centre of our own galaxy, the Milky Way. Surprisingly, it is harder to detect than M87's black hole, which is 55 million ligh-years away. This is because the light halo around the black hole of the Milky Way is smaller and not so clear.
Sources
No comments:
Post a Comment