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Quasar mass. Quasar - what is it? Gravity creates lenses




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Quasar- the active nucleus of the galaxy at the initial stage of development: research, description and characteristics with photos and videos, a powerful magnetic field, structure and types.

The most interesting thing in science is to find something unusual. At first, scientists do not understand at all what they are faced with and spend decades, and sometimes centuries, to understand the phenomenon that has arisen. So it was with the quasar.

In the 1960s, terrestrial telescopes faced a mystery. From , and some came radio waves. But unusual sources were also found that had not been observed before. They were tiny, but incredibly bright.

They were called quasi-stellar objects ("quasars"). But the name did not explain the nature and reason for the appearance. At the initial stages, we only managed to find out that they are moving away from us at 1/3 the speed of light.

- incredibly interesting objects, because with their bright radiance they can outshine entire galaxies. These are distant formations, powered by , and are billions of times more massive than the Sun.

The first received data on the amount of incoming energy plunged scientists into a real shock. Many could not believe in the existence of such objects. Skepticism led them to look for another explanation for what was happening. Some thought that redshift did not indicate distance and was related to something else. But subsequent studies rejected alternative ideas, because of which we had to agree that we really have one of the brightest and most amazing universal objects in front of us.

The study began in the 1930s when Carl Jansky realized that the statistical interference on transatlantic telephone lines originated from the Milky Way. In the 1950s scientists used radio telescopes to study the sky, and combine the signals with visible observation.

It is also surprising that there are not so many sources for such an energy reserve in a quasar. The best option is a supermassive black hole. This is a certain area in space, which has such a strong gravity that even light rays cannot escape from it. Small black holes are created after the death of massive stars. The central ones reach billions of solar masses. One more thing is surprising. Although these are incredibly massive objects, they can reach . No one can understand how such supermassive black holes form.

An illustration of a quasar and black hole similar to APM 08279+5255 where a lot of water vapor has been seen. Most likely, dust and gas form a torus around a black hole

A huge cloud of gas revolves around a black hole. Once gas enters a black hole, its temperature rises to millions of degrees. This causes it to create thermal radiation, making the quasar as bright in the visible spectrum as it is in the X-ray.

But there is a limit called the Eddington limit. This figure depends on the massiveness of the black hole. If a large amount of gas enters, strong pressure is created. It slows down the gas flow, keeping the brightness of the quasar below the Eddington line.

You need to understand that all quasars are far away from us. The closest one is located 800 million light years away. So, we can say that in the modern Universe they are no longer left.

What happened to them? Nobody knows for sure. But, based on the power source, then most likely the whole point is that the fuel supply has gone to zero. The gas and dust in the disk ran out, and the quasars could no longer shine.

Quasars - Remote Lights

If we are talking about a quasar, then we should explain , what's happened pulsar. It's fast spinning. It is created during the destruction of a supernova, when a highly compacted core remains. It is surrounded by a powerful magnetic field (1 trillion times greater than Earth's), which causes the object to generate noticeable radio waves and radioactive particles from the poles. They contain various types of radiation.

Gamma pulsars produce powerful gamma rays. As the neutron type turns towards us, we notice radio waves whenever one of the poles points to us. This sight is reminiscent of a lighthouse. This light will flicker at different speeds (size and mass affect). Sometimes it happens that a pulsar has a binary companion. Then he can invade the companion's matter and speed up his rotation. At a fast pace, it can pulse 100 times per second.

What is a quasar?

There is no exact definition for a quasar yet. But recent evidence suggests that quasars may be created by supermassive black holes that devour matter in an accretion disk. As the rotation speeds up, it heats up. Collisions of particles create a large amount of light and transfer it to other forms of radiation (X-rays). A black hole in this position will feed on matter equal to the solar volume per year. In this case, a significant amount of energy will be ejected from the server and south poles of the hole. This is called cosmic jets.

Although there is an option that we have young galaxies in front of us. Since little is known about them, the quasar may represent only an early stage of ejected energy. Some believe that these are remote spatial points where new matter enters the Universe.

Nature of cosmic radio sources

Astrophysicist Anatoly Zasov about synchrotron radiation, black holes in the nuclei of distant galaxies and neutral gas:

Search for quasars

The first quasar found was named 3C 273 (in the constellation Virgo). It was found by T. Matthews and A. Sanjage in 1960. Then it seemed that it refers to the 16th star, like an object. But three years later, they noticed that he had a serious redshift. Scientists guessed what was the matter when they realized that intense energy is produced in a small area.

Now quasars are found thanks to redshift. If they see that the object has a high it, then it is entered in the list of applicants. To date, there are more than 2000 of them. The main search tool is the Hubble Space Telescope. With the development of technology, we will be able to reveal all the secrets of these mysterious universal lights.

Light jets in quasars

Scientists think pinpoint glimmers are signals from galactic nuclei that eclipse galaxies. Quasars can only be found in galaxies that are supermassive (a billion solar masses). Although the light is not able to escape from this place, some particles make their way near the edges. While dust and gas are sucked into the hole, other particles move away at almost the speed of light.

Most of the quasars in the universe have been found billions of light years away. Let's not forget that the light takes time to reach us. Therefore, studying such objects, we seem to be returning to the past. Many of the 2000 found quasars existed at the beginning of galactic life. Quasars are capable of generating energy up to a trillion electric volts. This is more than the amount of light from all the stars in the galaxy (10-100,000 times brighter than the glow of the Milky Way).

Spectroscopy of quasars

Physicist Alexander Ivanchik on determining the primary composition of matter, cosmological epochs and measuring fundamental constants:

Types of quasars

Quasars are included in the class of "active galactic nuclei". Among others, you can also notice the Seyfert galaxies and. Each of them needs a supermassive black hole to feed.

Seyfert ones are inferior in energy, creating only 100 keV. Blazars consume much more. Many believe that these three types are the same object, but from different perspectives. The jets of quasars flow at an angle in the direction of the Earth, which blazars are also capable of. The Seyfert jets are not visible, but there is an assumption that their emission is not directed at us, therefore it is not noticed.

Quasars show the early structure of galaxies

By scanning the oldest universal objects, scientists manage to understand how he looked in his youth.

The Atakama large millimeter-wave array is capable of capturing the "infant" state of galaxies like ours, displaying the moment when stars were just born. This is surprising, because they return to a period when the universe was only 2 billion years old. That is, we are literally looking into the past.

By observing two ancient galaxies at infrared wavelengths, scientists have noticed that early in their development there are what appear to be elongated disks of hydrogen gas, larger than the much smaller inner star-forming regions. In addition, they already had rotating disks of gas and dust, and stars appeared at a fairly fast rate: 100 solar masses per year.

Objects under study: ALMA J081740.86+135138.2 and ALMA J120110.26+211756.2. The observations were aided by quasars whose light came from the background. We are talking about supermassive black holes around which bright accretion disks are concentrated. It is believed that they play the role of centers of active galaxies.

Quasars shine much brighter than galaxies, so if they are located in the background, then the galaxy is lost from sight. But the ALMA observation captures infrared light from ionized carbon, as well as hydrogen in the glow of quasars. The analysis shows that carbon creates a glow at a wavelength of 158 micrometers and characterizes the galactic structure. The birthplaces of stars can be found thanks to the infrared light from the dust.

Scientists have noticed another thing in the luminous carbon - its location was shifted in relation to gaseous hydrogen. This is a hint that the galactic gases move extremely far from the carbon region, which means that a large hydrogen halo can be found in each galaxy.

The term is formed by a combination of two words - quasistellar (similar to a star) and radiosource (radio emission). It is understood that the quasar is a quasi-stellar source of radio emission.

Beacons of the Universe

More than half a century has passed since the discovery of the first quasars. It is difficult to name the number of known objects due to the lack of clear distinctions between quasars and other types of galaxies with active nuclei. If at the end of the 20th century about 4,000 such objects were known, today their number is approaching 200 thousand. By the way, the initial opinion that all quasars are a powerful source of radio emission turned out to be erroneous - only a hundredth of all objects meet this requirement.

The brightest and closest quasar to the solar system (3C273, one of the first discovered) is located at a distance of 3 billion light years. Radiation from the most distant (PC1247+3406) travels the path to the earth observer in 13.75 billion years, which is approximately equal to the age of the Universe, i.e. now we see it as it was at the time of the Big Bang. A quasar is the most distant observable object in boundless outer space.

Wrong radiation

Scientists were baffled by the very first discovered quasar. Observations and spectrum analysis had nothing to do with any of the known objects so much that they seemed erroneous and unrecognizable. In 1963, the Dutch astronomer M. Schmidt (Palomar Observatory, USA) suggested that the spectral lines are simply very strongly shifted to the long wavelength (red) side. Hubble's law made it possible to determine the cosmological distance to the object and the speed of its removal from the redshift, which led to even greater surprise. The remoteness of the quasar turned out to be monstrous, and at the same time it looked through the telescope like an ordinary star of +13m magnitude. Comparison of the distance with the luminosity gave the mass of the object in billions of solar masses, which even theoretically cannot be.

Comparison of the spectral characteristics of quasars with data from galaxies of various types leads to interesting conclusions. The following structure of a smooth change of properties is found:

  • normal galaxies(types E, SO - radio emission is many times weaker than optical) - the closest, with the usual spectrum.
  • Elliptical(type E, with a clear spiral shape and the absence of blue-white giant stars and supergiants).
  • radio galaxies(radio emission power up to 10 45 erg/s).
  • Blue and compact(remote, high redshift and high brightness).
  • Seyfert(with active core).
  • Lacertides- powerful sources of radiation in the active nuclei of some galaxies, characterized by high brightness variability.

The latter are much less distant than quasars, and together with them form a class of blazars. According to scientists, blazars are active galactic nuclei associated with supermassive black holes.

World Eaters

How can this be? After all, a black hole has such a super-powerful gravitational field that even light cannot leave it. A quasar is the brightest object, considering the distance to it.

The source of electromagnetic radiation is the gravitational forces of a black hole located in the center of the galaxy. They attract the stars that have fallen into the field, and destroy them. The resulting gas forms an accretion disk around the black hole. Under the influence of gravity, it contracts and acquires a high angular velocity, which leads to strong heating and generation of radiation. The matter from the inner regions of the disk, not absorbed by the black hole, goes to the formation of jets - narrowly directed streams of elementary particles with high energy, formed under the action of a magnetic field from opposite poles of the galaxy nucleus. The length of the jets can range from several to hundreds of thousands of light years and depends on the diameter of the object's accretion disk.

Point of view

The above theory is the most popular, explaining most of the observed properties of "deadly" astronomical bodies. A less common version is that the quasar is the "embryo" of the galaxy, the formation of which is taking place before our eyes. But all scientists are unanimous in the opinion that these objects are phenomena of an optical nature. One and the same body can be identified as a Seyfert or radio galaxy, as a lacertide or a quasar. It matters at what angle it is located to the observer:

  • If the observer's gaze coincides with the plane of the accretion disk screening the processes in the active nucleus, he sees a radio galaxy (in this case, most of the radiation lies in the radio range).
  • If - with the direction of the jets, then a blazar with hard gamma radiation.

But, as a rule, the object is observed at an intermediate angle, at which most of the total radiation is received.

Glow dynamics

The fundamental property of quasars is the change in luminosity over short periods of time. Thanks to this, it was calculated that the diameter of a quasar cannot be more than 4 billion km (the orbit of Uranus).

Every second, a quasar emits a hundred times more light energy into space than our entire galaxy (the Milky Way). To maintain such a colossal productivity, a black hole every second must "swallow" the planet no less than the Earth. With a lack of matter, the intensity of absorption weakens, the functioning slows down, and the luster of the quasar weakens. After approaching and capturing new "victims", the luminosity returns to normal.

Unfriendly neighbors

Knowing the dangerous properties of these powerful energy sources, it remains to thank the universe that they were found only at a great distance, and in our and in the nearest galaxies they are absent. But isn't there a contradiction here with the Theory of Uniformity of the Universe? When looking for an answer, it should be taken into account that we observe these objects as they were billions of years ago. I wonder what a quasar is in our time, today? Astronomers are actively surveying nearby space structures in search of former super-powerful sources that have used up their "fuel". We are waiting for the results.

Scientists use known objects as a cosmological tool to study the properties and determine the main stages in the evolution of the Universe. Thus, only the discovery of quasars made it possible to draw conclusions about the difference from zero of the vacuum energy, to formulate the main problems of the search for dark matter, to strengthen confidence in the important role of black holes in the formation of galaxies and their further existence.

Contradictions. Time will show

There are quite a few judgments about how a quasar works and how it functions. Reviews of experts about various theories are also presented in a wide range: from ironic to enthusiastic. But there are objects with a number of properties that have no possible explanations.

  • Sometimes for the same quasar, the redshift value differs by 10 times, therefore, the object changes the removal speed by the same amount. Why not mysticism?
  • If, when observing two quasars moving away from each other, we estimate the distance to them by their redshift, then the speed with which they scatter will be higher than the speed of light!

These phenomenal results are obtained from the Big Bang theory, due to the general theory of relativity. Is there something wrong with the theory? In general, a quasar is a phenomenon that is still waiting for its researchers!

The Quasar Arm metal detector (in English quasar arm) is a selective, IB device created and designed by Andreev Fedorov, aka Andy_F. This device has become a continuation of the Quasar line on microcontrollers, in this case on the controller of the STM32 family.

In this article, we will look at its characteristics, field tests and consider the materials that we may need in case we wish to make it ourselves. Many more people are interested in such a question, does he distinguish metals? But here it is noticeable to the naked eye that the metal detector quasar arm (quasar arm) with discrimination.

Specifications Quasar Arm:

  • The supply voltage is from 6 to 15 volts.
  • Current consumption - an average of 150 to 200 mA, depending on the settings.
  • Multitonality is present.
  • Sector masks are present.
  • Operating modes - dynamics and statics.
  • Operating frequency - it all depends on the sensor, from 4 to 20 kHz.
  • The principle of operation is single-frequency, IB.

These are not all characteristics, but they give a general idea of ​​\u200b\u200bthe device. If you have not yet turned around and are ready to assemble the quasar arm with your own hands, then let's analyze what we need to assemble it.

Quasar arm diagram

Let's talk about the scheme md quasar arm, it will be provided below. In general, this is a rather complicated device and it is not suitable for beginners, here you need to understand the processes and have soldering experience. This is how the quasar arm diagram looks like:

By the way, we are enclosing a list of parts for this device, save it so as not to lose it.

Quasar arm board

Now let's talk about the printed circuit board, it looks like this:

Well, there is nothing to say here, download, print and etch. Note that some are interested in ordering boards from China. There is such an opportunity, there are manufacturers on the same Aliexpress, just write to them in a personal, throw off the fee in .lay, pay and wait until they send it. The boards are made on professional equipment and are of decent quality. The disadvantages of this method are that most do not work individually (I got from 5 pieces), and the price for a large number is already quite high. But if you order for sale or with friends, then there is no problem.

coil quasar arm

So we moved on to the moment of making a coil for a quasar arm metal detector, it was decided not to describe everything, but to show a video. Because it's better to see once than hear 100 times, well, in this case, read. This 20-minute video tells how to make a sensor with your own hands, about coil mixing and much more, there are also useful comments under the video.

Here is the diagram, it is the same as in previous versions of the device.

Quasar arm setting

Now let's talk about what the setup of the quasar arm metal detector is. Just like that, the device will not work, or it will not work correctly. You need to make settings, of which there are a lot in it, you also need to be able to calibrate the device and tune out from the ground.

It's all a long song, if everything is described. And again the saying about what is better to see once comes to mind. So we are putting together a fairly detailed video about its settings.

This video is from a fairly competent person who assembles these gadgets. And to paint each item of its settings - it makes no sense, a monkey's work in general. If you can't set it up, then watch this video. We talked about setting up the MD quasar, learned how to set it up, and moved on.

firmware quasar arm

As for the firmware, version 2.2.3 is now relevant, if you need an earlier one, then visit the author's website. Now about how to flash a quasar arm. We will attach a video, of course there is an older firmware, but the principle is the same, there is nothing to paint here either.

Quasar arm block

You can make a block yourself by making it from any beautiful box. They also sell ready-made boxes for the quasar, they are made to size and have a beautiful look. Good blocks are sold on Chinese sites, there is also a fairly large selection. Here is the sticker for the device:

So, the block of the metal detector quasar arm was dismantled, let's move on.

Quasar arm instruction

This is not a simple device and you can not do without instructions. In the manual you will find troubleshooting, answers to many questions, for example: repair of a quasar arm, problems with a weak sensor and input amplifier, information on a quasar arm with fm and other malfunctions of this metal shocker. Also, if the video is not enough for you, then there will be information on the quasar arm menu.

Metal detector quasar arm reviews

I believe that if you read this article, then everything is clear. A good and high-quality unit is this Quasar arm. Of course, there are some nuances, but in terms of parameters it surpasses many industrial units. I would like to note that if you purchase a ready-made device, then treat the choice of the artist very well. Because the quality directly depends on the assembly, but the prices for this device are different from manufacturers. We do not recommend taking from those who sell used or individual schemes (not a store and not a master), you may be left without support if the seller disappears. Find those who have a lot of reviews.

Quasar arm video

Here are a couple of videos from the quasar arm, here is a cop with it and video tests. Take a look and see if you need it. Also a comparison video - Koschey 25k against a quasar arm.

So we figured out how to make a quasar arm metal detector with our own hands, I hope the article was useful for you.

The first quasars were discovered by scientists in the early 60s of the last century. To date, they have already discovered about 2 thousand. They are the brightest objects in the universe and have a luminosity 100 times greater than all the stars in the Milky Way galaxy. The dimensions of the quasar are approximately equal to the diameter of the solar system - 9 billion km. it has a mass equal to 2 billion solar masses or more. Quasars are the central stars of various sizes of galaxies and large star systems. They are located at a distance of 2 to 10 billion light years from Earth. Quasars generate 2 energy jets - jets in different directions of the plane of their galaxies, the radiation energy of which is tens of thousands of times greater per second than that of the largest galaxies. What are the functions of quasars in the Universe?

Answer

Scientists do not know what source of colossal energy supports the luminescence of the quasar and why the emission of jet jets of such enormous power is needed. A quasar is a special type of star, similar to black holes in the center of galaxies, which has tremendous gravity and converts absorbed matter into energy and elementary particles, but has additional capabilities for radiating it into space. Quasars, like, absorb matter, but not only their own galaxy, but also those nearby. As in an ordinary black hole, inside a quasar any absorbed matter decays into elementary particles and energy, and then is emitted in the form of light quanta, infrared and X-rays, gamma radiation, radio waves and a huge spectrum of elementary particles, including neutrinos.

The quasar radiates all this energy and matter into space in the form of two opposite jets. Both jets contain the matter of time in the form of gamma radiation, neutrinos and other particles that are directed in different directions into the past and into the future to replenish their energy. The rest of the energy and elementary particles are absorbed by the intergalactic space, which is dark matter. To understand this process, one can imagine how a galaxy with a quasar in the center moves through the Universe at a speed of 0.6 - 0.85 of the speed of light and throws out huge energy in the form of 2 jet jets several billion km long. This energy is absorbed, which uses it to build new types of matter, new stars and galaxies.

Any level of mind can be created by the Creator in any form of matter or energy. Intelligent quasars convert matter into energy and elementary particles and transmit it using the radiation of intelligent dark matter, which, according to the programs set by the Creator of the Universe, re-creates new matter with the necessary properties and parameters for new experiments. Therefore, quasars and dark matter are the tools of the Creator to create new worlds in the Universe.

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Seyfertop galaxies are relatively close to us, and most radio galaxies are at medium distances. Much further in space, quasars are the most powerful sources of energy. The discovery of quasars required careful, almost detective research.

This story begins in 1960. Radio astronomers have perfected their methods for pinpointing the location of radio sources. The radio source 3C48 seemed to coincide with one star, unlike any other: bright lines were present in the whole spectrum, which could not be correlated with any of the known atoms. Then, in 1962, another mysterious star appeared to coincide with another radio source, 3C 273.

The word "quasar" was coined as short for "quasi-stellar radio source". "Quasi-stellar" means "resembling a star, but not a star." Astronomers now believe that quasars are the brightest of the varieties of active galactic nuclei. Thousands of quasars have already been discovered.

Although the first ones were found by radio astronomers, only one tenth of the quasars known today emit radio waves. In photographs, they look like stars (meaning they are small compared to galaxies), but they all have a large redshift. The largest redshift almost reaches 5. In this case, the wavelength of light sent by the quasar is stretched by about 6 times. This distortion is much stronger than for most galaxies, although some extremely faint, high redshift galaxies have been detected to date with the largest telescopes.

Light from distant quasars travels billions of years, so quasars tell us about conditions that existed in the universe a very long time ago.

Where are quasars located?

Most quasars have very large redshifts. Edwin Hubble showed how to determine the distance to a galaxy from the redshift of a galaxy. Can we apply the same method to quasars? With other elephants, does the quasar's redshift indicate its distance from us? According to many astronomers, this is so: they believe that quasars follow Hubble's law.

The large redshifts of quasars mean that they are very far away, at distances of billions of light years. Quasars are important to astronomy for two reasons. First, in order to see them and our telescopes from such a huge distance, they must release an incredible amount of energy. Second, because their light takes billions of years to reach us, quasars can tell us about conditions that existed in the universe a very long time ago. Astronomers want to find out what makes quasars glow so brightly, and by observing the most distant quasars, you can see what the universe was like long before the birth of the sun.

Observation of active centers

Active galaxies and quasars produce much more energy than normal galaxies, which is why we can see them at such great distances. In ordinary galaxies, almost all the light is emitted by normal stars. In high-energy galaxies, the total amount of energy emitted far exceeds the production of stars. Very detailed maps compiled by radio astronomers show that the vast majority of the excess energy comes from the central regions of galaxies.

Black holes in galaxies

Now many are sure that the cores of energetically active galaxies serve as a refuge for giant black holes. Probably, their masses are in the range from several thousand to several billion solar masses. The Hubble Space Telescope has detected whirlpools of matter revolving around black holes. Once a scoop hole has formed, it keeps getting bigger as matter is drawn in from the surrounding areas. In giant galaxies like M87, the central black hole can devour the equivalent of several stars in a day.

The black hole and the disk surrounding it are constantly filled with new portions of matter. The central regions of galaxies are densely filled with stars. Very dense star clusters can replenish fuel supplies. It could be gas that escaped from the surface of normal stars during their evolution, or it could be debris from a very large number of supernova explosions. As the black hole becomes more massive, the growing strength of its gravitational field allows it to more easily capture stars and tear them to shreds.

In normal stars, energy is released when hydrogen is converted into helium during nuclear fusion. This process converts and energy less than 1 percent of the mass. A spinning black hole is much more efficient. For most high-energy galaxies in the universe, the main source of energy seems to be not nuclear burning inside normal stars, but the action of a rotating black hole.

Quasars

Quasars are the most distant objects that can be seen with a telescope. Some quasars are 15 billion light-years away from us. When light from a very distant quasar passes through a cluster of galaxies, the path of the light beam bends.

Thousands and thousands of quasars are now known, and almost all of them are several billion light years away from our Galaxy. The most distant quasars fly away from us at speeds up to nine-tenths of the speed estimate. To detect very distant objects, astronomers examine many faint objects. With the help of large optical telescopes, it is possible to obtain the spectra of hundreds of such objects per night, which speeds up the search for quasars with high redshifts.

Very distant objects give astronomers the ability to travel through time. When we see a star or galaxy 10 billion light-years away, we are seeing something that is 10 billion years younger than our galaxy is now, at the moment of observation. This happens because the journey to us takes the light of 10 billion years. Undoubtedly, over billions of years, distant galaxies have changed a lot.

By observing distant galaxies, astronomers do what historians cannot: astronomers can actually look back into the past of the universe and directly see what conditions existed before, while historians use the far from complete evidence that has survived from past times.

One of the reasons larger and more efficient telescopes are needed is that by observing the most distant parts of the universe, we can learn about what it was like in the past. We see these objects at a time when galaxies were just beginning to form.

Gravity creates lenses

Einstein's theory of gravity states that light, passing through a strong gravitational field, bends its trajectory. The famous test of this theory was carried out during a solar eclipse in 1919. The positions of the stars observed near the solar disk changed slightly due to the fact that the rays of light, passing very close to the Sun, deviated somewhat from a straight line.

Quasars also show this effect, but in a much more dramatic way. Quasars rarely appear in the sky next to each other. But in 1979, astronomers discovered a pair of identical quasars very close to each other. In fact, these turned out to be two images of the same object, the light from which was distorted by a gravitational lens. Somewhere along the path of the beam of light coming from this quasar, there is something very dense and massive. The gravity of this object splits the light into a double image.

Many gravitational lenses are now known. Some of them create multiple images of distant quasars. In other cases, a distant quasar blurs into a beautiful glowing meadow. The visual illusion occurs because light from distant quasars passes through clusters of galaxies on its way to Earth. If there is a densely concentrated mass in such a cluster - for example, a giant black hole or a huge elliptical galaxy - then a distorted image arises.