Achieved the first image of Sagittarius A*, the black hole at the center of the Milky Way


In it center of our galaxyabout 26,000 light years from our mother planet, there is a part of the cosmos where the Gravitational force it is so and so strong that nothing, not even light, can escape from it. It is the supermassive black hole Sagittarius A* (or SgrA*, with trailing asterisk, yes); a monstrous astronomical object in the middle of the Milky Way with a mass equivalent to four million times that of our Sun. Its existence was detected for the first time in 1974 but it was not until today, almost fifty years later, that we have finally been able to see his shadow. An international team of scientists, with several Spaniards among their ranks, presented this Thursday the first direct image of the closest supermassive black hole to Earth.

The image has been captured thanks to international consortium known as Event Horizon Telescope (EHT, in its acronym in English); a global network of eight instruments scientists of the highest precision that, working in a synchronized manner, have managed to emulate the power of a “gigantic virtual telescope” of the size of our planet. One of the key points of this network has been the Pico Veleta radio telescope in Granada, located in the heart of Sierra Nevada. To give you an idea of ​​the magnitude of this instrument, the ‘terrestrial equivalent’ would be to have a camera with sufficient resolution to be able to reading a newspaper in new york from a cafe in Paris. or for photograph from Barcelona a golf ball located off the coast of Greenland. EITHER draw an orange on the surface of the Moon.

The spectacular image of this gravitational monster of 44 million kilometers in diameter supposed”the first the first visual confirmation that the object at the center of the galaxy it’s a black hole“explained the researcher Jose Luis Gomez, from the Institute of Astrophysics of Andalusia (CSIC), during the official presentation of the finding. “These unprecedented observations have greatly enhanced our understanding of what is happening in the center of our galaxy and offer new insights into how giant black holes interact with their environment”, added Geoffrey Bower, from the Institute of Astronomy and Astrophysics, Academia Sinica (Taipei), at one of the press conferences held this Thursday.

historical image

The Sagittarius A* first portrait is actually a picture of his shadow. Or rather, of the objects surrounding this gravitational well. Given that the epicenter of this astronomical object is technically impossible to photograph (because if there is no light there is no possible photography either), the image of this black hole collects the wake of the objects orbiting around it. Like the small cluster of stars traveling 1,500 kilometers per second in the far reaches of this black hole. Hello glowing gas cloud that orbits the black hole at the center of the Milky Way and that, on its way, emits intense radiation.

The first snapshot Sagittarius A* debuts just three years after the publication of the very first image ever obtained of a black hole. At the beginning of 2019, the same scientific team that stars in the news of the day presented the image (until then unpublished) of the ‘gravitational monster’ located in the center of the elliptical galaxy Messier 87to some 50 million light years from the earth. But unlike that first image, Sagittarius A* appears as a much more convulsive black hole. While in the black hole of Messier 87 the gas took between days and weeks to complete its orbit, in Sagittarius A* the orbits barely last a day. For this reason, as explained by the scientific team in charge of their study, they have had to calibrate about 10,000 million of observations to draw the silhouette of this astronomical body.

The resemblance between the image of Sagittarius A* and of Messier 87, the researchers enthusiastically explain, it also suggests that all black holes in the universe must have a similar structure. “The universe is full of donuts“, joked Rocco Lico, one of the scientists who has contributed to capturing this spectacular snapshot, pointing to the first images of this astronomical object.

direct test

Related news

After the publication of the image of the black hole at the center of the Milky Way, there are already two snapshots that we have some enigmatic celestial objects that, until a handful of years ago, he had only proven his existence on paper. In 1921, the German physicist Albert Einstein predicted, in his theory of general relativity, the presence of places where the fabric of the space-time is distorted in such a way that nothing, not even light, can escape from them.

For almost a hundred years, the only way to prove the existence of black holes was through indirect evidence that would show that, indeed, there was something that deformed the spatial mesh. But the publication of the first images of these massive monsters unequivocally confirms the existence of these astronomical objects. He also confirms that the theoretical framework that has guided the study of the universe in recent decades is still valid.


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