Black Hole and the Science Behind It

this isn't just cosmic noise. This is NASA X-ray data converted into sound. They contain a hidden trace of an ancient flash in the very center of the Milky Way. a flare so powerful that if Earth were closer to the galactic center, this X-ray storm would completely destroy our ozone layer. The source of this moon is the Sagittarius supermassive black hole. And today this gravitational monster hardly eats. The gas approaches the event horizon and often simply flies past it. The black hole is so hungry that by the standards of active galactic nuclei, it is practically asleep. Even when massive gas clouds passed very close, scientists expected a flare, but the black hole absorbed almost nothing. The matter heated, stretched, rotated around the center,

and then moved away. But the data behind that sound tells a different story. Just 200 years ago, our invisible black hole woke up and emitted a flash about a million times brighter than today. This was one of the most powerful displays of galactic center activity in the last century. On Earth, this event went completely unnoticed. We were saved by a distance of 26,000 light years and dense clouds of cosmic dust. But right now, a deadly echo is sweeping through the galaxy. Where did this outbreak come from? What exactly did the shooter swallow? And how were scientists able to prove this two centuries later in their search for the shooter? A. But first, how do we even know that there is a black hole at the center of our galaxy? For a

long time, this region was a complete blind spot for scientists. Optical telescopes are powerless here. Our view needs to penetrate 26,000 light years of dense cosmic dust. Humanity got its first clue purely by chance. In 1932, radio engineer Karl Jansky built a rotating antenna to study atmospheric interference. But instead of terrestrial thunderstorms, he recorded a constant hissing. This background noise came from the constellation Sagittarius, precisely from the direction where we know today that the dust-shrouded center of our galaxy lies. Jansky became the first person to detect radio noise from the core of the Chuman path,

the same region where the shooter would later be discovered. However, in the midst of the Great Depression, the laboratory management denied him further funding. The engineer was transferred to another project, and this mysterious signal went largely unnoticed for many years. To finally unravel the nature of this object, astrophysicists Andrea Hess and Reingerd Henzel had to make a technological breakthrough. In the 1990s, armed with infrared telescopes capable of seeing through dust, they began a decade-long experiment. They began to track the trajectories of stars. At the very center of the galaxy, their observations became one of the most important pieces of evidence in modern astronomy. One of S2's key stars

completes a complete orbit around this invisible mass in just 16 years, accelerating to 1000 km/sq km during its closest approach. For comparison, our sun moves around the center of the Milky Way tens of times slower. The laws of orbital mechanics are not in vain. To force a massive star to move along this trajectory, an enormous gravitational pull must be concentrated in this dust cloud. Orbital calculations showed that the mass of this invisible object is almost 4 million times that of our suns. However, the orbits of the nearest stars imposed strict limits on the size of this region. All this mass was concentrated in an area smaller than our

solar system. Any cluster of ordinary dark objects packed so tightly would inevitably collide and collapse. Of all known physics, only one convincing explanation remains. Such a compact mass could only be a supermassive black hole. And according to Einstein's equations, the event horizon of such an object would have a diameter of only about 13 million km. This titan, gravitationally governing these stars, turned out to be four times smaller than the distance from our sun to Mercury. For this elegant proof, Hess and Hensel received the 2020 Nobel Prize in Physics. It took decades to obtain this proof

. They had to track the orbits of stars around the galactic center for quite some time. And the orbit of that same star C2 lasted 16 Earth years. The paradox of the hungry hole. So, we know that Sagittarius A has a huge mass, but mass alone does not mean that the black hole is constantly pulling in or pulling in everything around it. It all comes down to the physics of orbital motion. There is gas around it, but by the standards of active nuclei, galaxies, this is very little fuel. There is very little matter and it is extremely rarefied, and it has a hard time losing its angular momentum. For matter to fall beyond the

event horizon, it must slow down due to internal friction. Astrophysicists observed this mechanism in real time. In 2012, telescopes spotted an object called G2, whose trajectory was supposed to bring it extremely close to Sagittarius. And the scientific world held its breath in anticipation. Researchers expected that some of its matter would be torn off and begin falling onto the black hole. But when G2 reached its point of maximum convergence in 2014, the expected large-scale accretion unfortunately never happened. The extreme gravity only stretched it into a long thread, after which G2 flew past the black hole and continued its orbit. Similarly, some of the matter in the galactic center continues

to rotate without falling inward. Our galactic core survives on strict rations, and this makes the paradox even stronger. If even the close flyby of the G2 object did not cause the expected flare, where did the echo of that massive event two centuries ago come from? The answer came not from the center itself, but from its outskirts. In the late 1990s, orbiting telescopes detected an anomaly. Giant molecular gas clouds around the galactic nucleus, normally cold and dark, glowed brightly in the X-ray range. The most convincing explanation was this: the clouds were not glowing on their own, they were reflecting a flash from an external

source. But what caused it 200 years ago? Was it the explosion of a nearby supernova? Was this incident provoked by the shooter himself? And to test this, astronomers had to trace the path of light back to its source, and polarization was the key. Ordinary radiation propagates in space chaotically. Its waves oscillate in all possible directions. But when an X-ray beam hits a gas cloud and is scattered, its properties change. Imagine that you are sending a wave along a long rope, pulling it in different directions. Now imagine a wooden fence with narrow vertical planks standing in the path of the rope. If a wave passes through these slits, it maintains only one direction of oscillation. Although gas clouds don't

literally work as a fence. The concept is similar. After interacting with the cloud, the light acquires a certain orientation of oscillations. In 2022, the IXP space observatory measured the plane of oscillation of this reflected light. The polarization angle was about -48° with a noticeable but very informative error. Knowing this angle and the coordinates of the glowing cloud itself, astrophysicists were able to determine the direction from which the original X-ray light came. Polarization worked like a compass. This line pointed directly to the shooter's neighborhood. And, as you might have guessed, now it was not just a beautiful hypothesis, but a geometric proof. Now we have the most important confirmation. About 200

years ago, the region around the Central Black Hole was indeed a source of intense X-ray flare. But how and why did this happen then, if the center is so hungry today? The most likely explanation is that about 200 years ago, a certain amount of matter lost orbital stability and approached Sagittarius A close enough to trigger a brief episode of accretion. What exactly was that? A dense gas cloud, debris from a ruptured object, or some other stream of matter, we don't know for sure. But the material in the internal accretion stream rapidly overheated, causing a powerful X-ray flare. This was a rare episode of active accretion amid his prolonged fasting. A photograph of the invisible. Mathematically proving

the existence of a black hole beyond the orbits of stars and finding traces of its ancient activity through X-ray echoes are monumental achievements. But that wasn't enough. Astrophysicists wanted more. Obtain an image of the region right near the event horizon. Sagittarius A is incredibly far away by astronomical standards. It's like trying to see a donut on the surface of the moon. no single telescope has this resolution. To get the necessary clarity, scientists literally had to turn our entire planet into a giant camera. This is how the Event Horizon Telescope project was born. Event horizon telescope.

Scientists have combined radio observatories on different continents: from Hawaii and the Atacama Desert to the ice of the South Pole. By perfectly synchronizing them using atomic clocks, they created a virtual radio telescope with the resolution of an instrument almost the size of the entire Earth. This is a really big telescope. In 2019, this network gave the world the first-ever image of a black hole's shadow. It was M87 with an asterisk. A colossal object in the distant galaxy M87. We saw not the hole itself, but a ring of hot gas glowing around a dark central region. But the image of Sagittarius A at the center of our galaxy was reconstructed only three years later. So you might ask, why was it more difficult to photograph

an object that is right next to us? The answer lies in gas dynamics. M87 with the star is more than 1,000 times more massive, so the gas around it changes much more slowly. To ground-based telescopes, it appeared almost perfectly still. But for Sagittarius A, the picture changes noticeably right in the middle of the observation. The gas around it rotates at breakneck speed. And because the A-shooter is so compact, a full rotation takes just a few minutes. The brightness and shape of the ring were constantly changing. For scientists, it was like trying to take a clear portrait of a running toddler using a long- exposure camera. The image inevitably blurred. The telescopes generated

so much data that it was impossible to even transmit it over the internet. This is a huge pile of data. We are talking about petabytes of information on hard drives that had to be transported by airplane to the central supercomputer complex. And it actually took years of processing to filter out the dynamic chaos, highlight the stable features, and reconstruct the image of this glowing ring. Looking at this shining halo, it is easy to imagine a true destroyer of worlds. But by the standards of the universe, a Sagittarius, but in reality practically a dwarf.

Let's compare the scales. The black hole M87, whose portrait we obtained first, has a mass of over 5 billion solar masses. Now let's look at the real leviathans. The object TON 618 has over 60 billion solar masses. If tone 618 is a boundless ocean, then our black hole is a small puddle after the rain. This leviathan is tens of thousands of times heavier than our black hole. This constant lack of fuel is the main reason why Sagittarius Anne shines like a quasar. It may seem massive to us, but on a cosmic scale. This is a rather modest object. So what would happen if there was enough matter, given a constant influx of dense gas? The galactic center could become an active galactic nucleus. The

inner regions of the accretion flow and the hot corona would heat up to extreme temperatures, emitting intense X-ray radiation. Magnetic fields in the accretion flow could form relativistic jets, streams of plasma that pierce space at speeds close to the speed of light. In the brightest cases, such a system can shine brighter than hundreds of billions of stars in its galaxy combined. It is truly extremely bright. For planets near the galactic center, such activity would be catastrophic. But Earth is located far from the core on the outskirts of the galactic disk.

Therefore, our safety is explained not only by the lack of fuel of the gunner A, but also by the fact that we are lucky to be so far away from it. Fortunately, our world exists in a relatively peaceful region of the Milky Way. But in the future, this silence may be broken by Andromeda. Right now, our neighboring galaxy is hurtling toward us. For a long time, a collision in a few billion years was considered inevitable, but recent calculations have made this outcome less certain. Today, this is no longer a guaranteed fate, but a more likely scenario. On a cosmic scale, galaxy collisions are an extremely complex gravitational interaction. If Andromeda and the Milky Way begin to pass through each other,

tidal forces will distort their structures. The stars themselves are unlikely to collide due to the vast distances between them. Gas clouds, however, are undergoing massive restructuring. Their orbits will be disturbed, and some of the matter will lose some of its angular momentum. and will start pointing towards the galactic centers. For a Sagittarius, this will mean one crucial thing. The starving core will finally get fuel. It will be able to draw in a powerful new flow of matter and temporarily become much more active. But this process is only a prelude. At the center of Andromeda is its own supermassive black

hole with a mass of up to 100 million suns. As galaxies merge, these objects will gradually begin to converge, moving in a spiral. If this galactic merger does indeed occur in the distant future, their central black holes could eventually meet and merge into a single, even more massive, supermassive black hole, releasing some of their energy in the form of gravitational waves. This is just one possible scenario, but we fundamentally cannot observe our galactic center in real time. Our observations are strictly limited by the speed of light. Due to the distance of 26,000 light years, we always see

Sagittarius A in the distant past. It is possible that it has had new episodes of accretion over these 26,000 years. It may have absorbed gas again, but the light from these events simply hasn't reached Earth yet. For now, we rely on mathematics, orbital mechanics, and data from X-ray telescopes. And they show the most important thing. At the center of the Milky Way lies not an abstraction, but a real physical object. Today he seems almost asleep. 200 years ago, he briefly woke up and in the distant future. If galactic dynamics feed it again, Sagittarius A could transform the quiet center of our galaxy into a dazzling beacon.

We don't live next to an empty dead center. We share the galaxy with a monster that hasn't disappeared, it just has n't really eaten in a very long time.