Capture in images a black hole is enough for an event to qualify as historical. It is hardly the second that it has been shown in a photograph in our entire existence and it was carried out after a meticulous investigation that took about five years.
The phenomenon grows when we stop at the fact that it is precisely the black hole that is in the Milky Way, in the heart of our galaxy. To this we have to add that the milestone of astronomy would not have been achieved without the tools strategically located in the Atacama desert, in Chile.
The ALMA (Atacama Large Millimeter/submillimeter Array) It was fundamental so that this Thursday, May 12, 2022, science celebrates a step forward in the exploration of the universe.
So, with the intention of knowing the true magnitude of this historical announcement of astronomy, we turned to the experts, to the voice of experience that has spent years devoting efforts to the investigation of the cosmos and the secrets that are hidden in the depths of the Earth. galactic region to which we belong.
And so, we were fortunate to have a pleasant chat with the astronomer Luis Chavarria Garridorepresentative of European Southern Observatory (ESO for its acronym in English) in Chili.
The importance of capturing our black hole
Black holes are the objects that hide the greatest secrets in our universe. Nothing escapes them and they can only be studied through the elements that surround it. So with the image we now have of Sgr A* (Sagittarius A*) what is really captured is the energy that shapes this shadow located in the center of the Milky Way.
Sgr A* is about 27,000 light years distant from Earth. and it is only the second to be photographed. The first had been M87a supermassive black hole in another galaxy located 55 million light years.
We asked Luis Chavarría Garrido why it took so long to capture the one in our galaxy, if it is closer than M87, and he immediately surprised us with the most amazing data of all.
The black hole in our galaxy is extremely small compared to the rest of those known to exist, “Sgr A* is just about the size of the orbit of Mercury.”
So, being so small, the elements that surround it move much faster due to the gravitational force that the hole prints on the bodies that are around it.
“We needed him to stay. still for photography. That is why it took us so long to analyze their data”, explained Luis (we are not ashamed). with pears and apples so that we could understand the technical details.
“Seeing this black hole is the equivalent of trying to find a donut on the surface of the Moon,” adds the representative of the THAT in Chile.
So how did they do it?
To capture such a small and distant black hole “there are two ways”, Luis tells us. “The first is with a telescope that is the size of the Earth. The larger the tool, the farther we can see. So since it is practically impossible to manufacture something so large, we put together several radio telescopes to turn them into one, ”he pointed out.
This process is not easy. Metaphorically speaking the planets have to be aligned so that several telescopes within a radius of 6 thousand kilometers can be emulated.
Telescopes have to be synchronized with atomic clocks. Then, in each region in which each of the tools is located, there must be good weather and that is when they can act to start collecting data in unison with time.
In the middle of all this configuration, they were the 66 antennas that are part of ALMA and the APEX project. Without them, it would not have been possible to assemble the image of the black hole of the Milky Way.
What comes after this…?
… We asked Luis. We see this image of a black background with an orange circle and we are curious what we are going to do with that photo.
The Chilean astronomer explains that from this moment, in addition to studying Sgr A*, a hunt for black holes in the universe begins.
“If we were able to detect this one, surely we will be able to capture others that we know exist and that are larger”, Luis Chavarría Garrido told us.
Knowing other black holes help us to know more details about the formation of galaxies that in turn have thousands of solar systems inside. Scientists were pleasantly surprised by the similarity in shape of M87 with Sgr A* despite the difference in size and distance between the two.
In this sense, the Chilean astronomer reveals to us the existence of black holes of all kinds of sizes scattered throughout the universe. “We know of the existence of black holes that have the same mass as our Sun.”.
In this way, studying this type of phenomenon, still with many mysteries to be solved and a universe of possibilities to discover, will make us understand what they generate with their existence, which occurs through a supernova explosion.
The shape it gives to a galaxy, the number of stars it forms, the gas it heats around it and its brightness are behaviors that must continue to be studied in detail in this and the next black holes that can be observed.