Dr. Jane Lisin Dai and Professor Enrico Ramirez-Ruiz from the Niels Bohr Institute presented an important computer model. It can be used to study tidal disruption events - rare but extremely powerful events in galactic centers.
Tidal disruption
At the center of each large galaxy hiding a supermassive black hole, which is millions and billions times more massive than the sun. But most are difficult to observe because they do not emit radiation. This happens when definite shape material is pulled into the extremely powerful gravitational field of the black hole. About every 10,000 years in one galaxy, a star comes dangerously close to the hole, and the latter's gravity tears the object apart. This event is called a gravitational tide.
In this process, the black hole is filled with stellar fragments certain time. When star gas is consumed, enormous amounts of radiation are released. Thanks to this, you can study the characteristics of the hole.
Unified model
At high tide, some holes emit X-rays, and others - visible light and UV. It is important to understand this diversity and put together the whole puzzle. In the new model, they tried to take into account the viewing angle of an earthly observer. Scientists study the Universe, but galaxies are oriented randomly.
The new model combines elements from general relativity, magnetic field, radiation and gas, making it possible to consider a tidal event with different points vision and collect all actions into a single structure.
Cooperation and prospects
The work was made possible through collaboration between the Niels Bohr Institute and the University of California, Santa Cruz. Researchers from the University of Maryland also got involved. Modern computing tools were used to solve the problem. The breakthrough provided perspective for a fast-growing area of research.
The concept of a black hole is known to everyone - from schoolchildren to the elderly; it is used in science and fiction literature, in the yellow media and on scientific conferences. But what exactly such holes are is not known to everyone.
From the history of black holes
1783 The first hypothesis of the existence of such a phenomenon as black hole, was put forward in 1783 by the English scientist John Michell. In his theory, he combined two of Newton's creations - optics and mechanics. Michell's idea was this: if light is a stream tiny particles, then, like all other bodies, particles must experience attraction gravitational field. It turns out that the more massive the star, the more difficult than the light resist its pull. 13 years after Michell, the French astronomer and mathematician Laplace put forward (most likely independently of his British colleague) a similar theory.
1915 However, all their works remained unclaimed until the beginning of the 20th century. In 1915, Albert Einstein published the General Theory of Relativity and showed that gravity is the curvature of spacetime caused by matter, and a few months later, German astronomer and theoretical physicist Karl Schwarzschild used it to solve a specific astronomical problem. He explored the structure of curved space-time around the Sun and rediscovered the phenomenon of black holes.
(John Wheeler coined the term "Black holes")
1967 American physicist John Wheeler outlined a space that can be crumpled, like a piece of paper, into an infinitesimal point and designated it with the term “Black Hole”.
1974 British physicist Stephen Hawking proved that black holes, although they absorb matter without return, can emit radiation and eventually evaporate. This phenomenon is called “Hawking radiation”.
Nowadays. Latest research pulsars and quasars, as well as the discovery of cosmic microwave background radiation, finally made it possible to describe the very concept of black holes. In 2013, the G2 gas cloud came very close close quarters towards a Black Hole and will most likely be absorbed by it, observations of a unique process will provide enormous opportunities for new discoveries of the features of black holes.
What black holes actually are
A laconic explanation of the phenomenon goes like this. A black hole is a space-time region whose gravitational attraction so great that not a single object, including light quanta, can leave it.
The black hole was once a massive star. Bye thermonuclear reactions support in its depths high pressure, everything remains normal. But over time, the energy supply is depleted and heavenly body, under the influence of its own gravity, begins to compress. The final stage of this process is the collapse of the stellar core and the formation of a black hole.
- 1. A black hole ejects a jet at high speed
- 2. A disk of matter grows into a black hole
- 3. Black hole
- 4. Detailed diagram black hole region
- 5. Size of new observations found
The most common theory is that similar phenomena exist in every galaxy, including the center of ours. milky way. The hole's enormous gravitational force is capable of holding several galaxies around it, preventing them from moving away from each other. The “coverage area” can be different, it all depends on the mass of the star that turned into a black hole, and can be thousands of light years.
Schwarzschild radius
The main property of a black hole is that any substance that falls into it can never return. The same applies to light. At their core, holes are bodies that completely absorb all light falling on them and do not emit any of their own. Such objects may visually appear as clots of absolute darkness.
- 1. Moving matter at half the speed of light
- 2. Photon ring
- 3. Inner photon ring
- 4. Event horizon in a black hole
Starting from General theory According to Einstein's relativity, if a body approaches a critical distance to the center of the hole, it will no longer be able to return. This distance is called the Schwarzschild radius. What exactly happens inside this radius is not known for certain, but there is the most common theory. It is believed that all the matter of a black hole is concentrated in an infinitesimal point, and at its center there is an object with infinite density, which scientists call a singular perturbation.
How does falling into a black hole happen?
(In the picture, the black hole Sagittarius A* looks like an extremely bright cluster of light)
Not so long ago, in 2011, scientists discovered a gas cloud, giving it the simple name G2, which emits unusual light. This glow may be due to friction in the gas and dust caused by the Sagittarius A* black hole, which orbits it as an accretion disk. So we become observers amazing phenomenon absorption of a gas cloud by a supermassive black hole.
By latest research The closest approach to the black hole will occur in March 2014. We can recreate a picture of how this exciting spectacle will take place.
- 1. When first appearing in the data, a gas cloud resembles a huge ball of gas and dust.
- 2. Now, as of June 2013, the cloud is tens of billions of kilometers from the black hole. It falls into it at a speed of 2500 km/s.
- 3. The cloud is expected to pass by the black hole, but tidal forces caused by the difference in gravity acting on the leading and trailing edges of the cloud will cause it to take on an increasingly elongated shape.
- 4. After the cloud is torn apart, most of it will most likely flow into the accretion disk around Sagittarius A*, generating shock waves in it. The temperature will jump to several million degrees.
- 5. Part of the cloud will fall directly into the black hole. No one knows exactly what will happen to this substance next, but it is expected that as it falls it will emit powerful streams of X-rays and will never be seen again.
Video: black hole swallows a gas cloud
(Computer simulation of how most of gas cloud G2 will be destroyed and absorbed by the black hole Sagittarius A*)
What's inside a black hole?
There is a theory that states that a black hole is practically empty inside, and all its mass is concentrated in an incredibly small point located at its very center - the singularity.
According to another theory, which has existed for half a century, everything that falls into a black hole passes into another universe located in the black hole itself. Now this theory is not the main one.
And there is a third, most modern and tenacious theory, according to which everything that falls into a black hole dissolves in the vibrations of strings on its surface, which is designated as the event horizon.
So what is an event horizon? It is impossible to look inside a black hole even with a super-powerful telescope, since even light, entering the giant cosmic funnel, has no chance of emerging back. Everything that can be at least somehow considered is located in its immediate vicinity.
The event horizon is conditional line a surface from under which nothing (neither gas, nor dust, nor stars, nor light) can escape. And this is the very mysterious point of no return in the black holes of the Universe.
Astrophysicists have recorded the longest death of a star in a black hole in the entire history of observations - the duration of the process exceeded similar cases by more than 10 times. The fact is that the black hole absorbs a star twice the mass of the Sun. According to scientists, over time active surveillance This is the first time in the Universe that such a large star has died in a black hole. Read about whether the discovered process can shed light on the formation of black holes of enormous mass a billion years after the origin of the Universe.
- The death of a star near the black hole XJ1500+0154 as imagined by an artist. At the bottom there is a photo of what is happening: in visible spectrum(left), in the X-ray range
- nasa.gov
Random opening
The process was recorded by an international group of scientists, whose work was led by Dachen Lin from the Space scientific center University of New Hampshire. Similar events in the memory of scientists took a maximum of about a year, while the process occurring at the black hole called XJ1500+0154 began back in 2005. The star, which died under the influence of tidal forces, was torn apart, and a supermassive black hole continues to absorb its remains.
Astrophysicists accidentally noticed X-ray radiation emitted by fragments of a star heated to millions of degrees using space telescope XMM-Newton. At that moment, they were studying a galaxy cluster called NGC 5813 in the constellation Virgo, 105 million light years from Earth. The strong radiation attracted the attention of scientists at the stage of analyzing images of NGC 5813. In 2008, the Chandra telescope recorded that the intensity of the radiation of an object that accidentally appeared in the image and was much further away from the galaxy cluster being studied exceeded the first recorded values by 100 times. In subsequent years, including 2014 and 2016, the Swift telescope received additional data.
The main thing is to eat right
“The object grows rapidly most of the time it is observed,” said James Gillochon of the Harvard-Smithsonian Center for Astrophysics. “This suggests something unusual: the black hole is consuming a star twice the mass of the Sun.”
According to scientists, during the active observation of the Universe, the death of such a large star in a black hole has been observed for the first time.
In addition, the researchers noted that the recorded X-ray radiation regularly exceeds the permissible limits of the so-called Eddington limit. This parameter indicates the ratio of the heated substance emitted and the gravitational force, which attracts the substance to the center of the object. Based on how this relationship breaks down around the observed black hole, astrophysicists have come to the conclusion that it is growing faster than what was considered normal. According to them, In a similar way Supermassive black holes could appear just a billion years after the formation of the Universe. This important conclusion, since ancient objects of such enormous mass - billions of times larger than the Sun - have already been recorded, but their origin is not completely clear.
Since the 1990s, astronomers have repeatedly observed the decay of a star and its absorption by a black hole. In this process, falling under the gravitational force of a massive object, the star breaks up into fragments. The substance of which it consisted is distributed in the form of a flat disk. Most of it is absorbed by the black hole, and the rest is scattered in space.
In a recorded case, in addition to death massive star There is another option, no less intriguing. If a star of more modest size approached the black hole and disintegrated completely, the observed effect would be the same. Complete absorption usually does not occur, so this event would have been seen for the first time in space exploration.
Last X-rays
The location of the black hole, which has already been jokingly called the most voracious one ever observed, coincides with the supposed location space object a huge mass in the center of a small galaxy, where star formation is actively taking place. There is obviously no need to talk about detailed photographs of what is happening at such a distance from Earth - 1.8 billion light years. However, artists presented their vision of the death of a huge star due to a black hole.
In the next few years, experts expect a drop in the intensity of radiation: the fragments of the huge star that feed the black hole will run out. Some of them will dissipate into space. Astrophysicists note that the radiation has already begun to decline, but the object still retains incredible brightness.
As the researchers stated, knowing about the possibility of processes with the properties that were identified, they will begin to search for similar cases. However, they note that they will continue to monitor XJ1500+0154. First, they will be able to track changes in radiation, which they predict will continue for about 10 years. Secondly, their own conclusions still require further verification.
Scientists suspected that the power of radio-emitting emissions from a black hole depends on the accretion rate, but had not previously observed this relationship directly.
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On November 11, 2014, a global network of telescopes received signals from an explosion that occurred 300 million light-years from Earth as a black hole tore apart a passing star. Astronomers targeted the event with other telescopes, allowing them to learn more about how black holes consume matter and regulate the growth of galaxies.
Scientists from the Massachusetts Institute of Technology(USA) and Johns Hopkins University (USA) caught radio signals that overlap 90% with those distant X-ray bursts, but occur with a delay of 13 days from them. They believe the evidence suggests a giant jet of high-energy particles flowing out of the black hole as a result of falling stellar material.
An artist's impression of a star being swallowed up by a black hole. Credit: ESO/L. Calçada
The study's lead author, Dehei Pasham, believes that the power of the jet escaping from the black hole is somehow controlled by the rate at which it feeds into the destroyed star. A "fed" black hole produces a strong jet, while a malnourished black hole produces a weak jet or no jet at all. Scientists suspected that the power of the emissions depended on the accretion rate, but had not previously observed this relationship directly.
Subject of discussion
Based on theoretical models evolution of black holes combined with observations of distant galaxies, scientists have general understanding of what happens during a tidal disruption event: when a star passes close to a black hole, the black hole's gravitational pull excites tidal forces on the star, similar to how the Moon creates ocean tides on Earth. The gravity of a black hole is so enormous that it can destroy a star. Stellar debris is caught in a vortex of material that feeds the monster.
The entire process generates colossal bursts of energy throughout electromagnetic spectrum. Scientists have observed them in optical, ultraviolet and x-ray bands, as well as radio waves. The source of the X-rays is believed to be ultra-cold material from the inner regions of the accretion disk that is about to fall into the black hole, while the optical and ultraviolet radiation likely comes from the outer regions of the accretion disk.
However, what generates radio emission during tidal disruption is still debated. Some scientists suggest that at the moment of the stellar explosion shock wave spreads outward and excites plasma particles into environment, which, in turn, emits radio waves. In such a scenario, the pattern of radio waves would be radically different from the pattern of X-rays emanating from stellar debris, and the new study challenges this paradigm.
Shift pattern
Dehei Pasham and his colleague Sjort van Velzen from Johns Hopkins University looked at data recorded from an outbreak discovered in 2014 global network ASASSN (All-sky Automated Survey for Supernovae) telescopes. Soon after this discovery, several telescopes focused on this unusual event. Scientists tracked radio observations from three telescopes over 180 days and found a clear match with X-ray data from the same event, albeit slightly shifted in time. Astronomers found that the data sets were 90 percent similar when shifted by 13 days. That is, fluctuations in the X-ray spectrum appeared in the radio range after 13 days.
“Such a dependence can only be determined physical process, which somehow links the X-ray emission of the accretion stream to the radio production region,” explains Dehei Pasham.
From the same data, scientists estimate that the size of the X-ray-producing region is about 25 times the size of the Sun, while the radio-emitting region is about 400,000 times the radius of the Sun. The team suggests that the radio waves are emitted by a jet of particles high energies, which began to flow out of the black hole shortly after absorbing material from the destroyed star.
Because the region of the jet in which the radio waves were generated is incredibly densely packed with electrons, most of the radiation was immediately absorbed by other electrons. Only when the electrons moved through the jet were the radio waves released. This was the signal that the researchers eventually discovered. Thus, the jet's power is controlled by the rate of accretion at which the black hole absorbs X-ray-emitting stellar debris.
Accidentally getting too close to a black hole will stretch you out like spaghetti.
Powerful radiation will fry you before you become spaghettized
Before you even know it, a black hole will devour the Earth.
And at the same time, a black hole can create a hologram of the entire planet
Black holes have long been a source of great excitement and intrigue.
After discovery gravitational waves, interest in black holes will certainly increase now.
One question remains unchanged - what will happen to the planet and humanity if we theoretically assume that a black hole will be close to the Earth?
The most famous consequence of the proximity of a black hole will be a phenomenon called “spaghettification.” In short, if you get too close to a black hole, you'll be stretched out like spaghetti. This effect is caused by gravity acting on your body.
Imagine that your feet were first in the direction of the black hole.
Since your feet are closer to the black hole, they will feel a stronger pull than your head.
Even worse, your arms, because they are not in the center of your body, will be stretched in a different direction than your head. The edges of your body will draw inward. Ultimately, your body will not only stretch out, but also become thin in the middle.
Consequently, any body or other object, such as the Earth, will resemble spaghetti long before it falls into the center of a black hole.
What would happen, hypothetically, if a black hole were suddenly close to the Earth?
The same gravitational effects, which could lead to “spaghettification” will immediately begin to take effect. To the side of the Earth that will be closer to the black hole, gravitational forces will act more strongly than on the opposite side. Thus, the death of the entire planet would be inevitable. It would have been torn apart.
If the planet were within the range of a super-powerful black hole, we would not even have time to notice anything, since it would swallow us in an instant.
But before the thunder strikes, we still have time.
If such a misfortune happened and we fell into a black hole, we could end up on a holographic likeness of our planet.
Interestingly, black holes are not necessarily black.
Quasars are bright nuclei of distant galaxies that feed on the energy of radiation from black holes.
They can be so bright that they exceed the radiation power of all the stars in their own galaxies.
Such radiation occurs when a black hole feasts on new matter.
To be clear, what we can still see is matter outside the black hole's radius. There is nothing within its range of action, not even light.
During the absorption of matter, colossal energy is emitted. It is this glow that is visible when observing quasars.
Therefore, objects caught in close proximity to a black hole, it will be very hot.
Long before "spaghettification" powerful radiation will fry you.
For those who have seen Christopher Nolan's Interstellar, the prospect of a planet orbiting a black hole can only be appealing in one way.
For life to develop, a source of energy or a temperature difference is necessary. And a black hole could be such a source.
However, there is one condition.
The black hole must stop absorbing any matter. Otherwise, it will emit too much energy to support life on neighboring worlds. What life would be like in such a world (provided that it is not too close, otherwise it will become “spaghettized”), but that is another question.
The amount of energy the planet will receive will likely be tiny compared to what Earth receives from the Sun.
And the habitat on such a planet will be quite strange.
That's why, when making Interstellar, Thorne consulted with scientists to ensure the image of the black hole was accurate.
All of these factors do not rule out life, it is just that it has a rather harsh outlook and it is very difficult to predict what it will look like.