Quasar mass. The most destructive object in the universe

A quasar is a galaxy at the initial stage of its development, in the center of which there is a huge supermassive black hole, the mass of which is billions of times greater than the mass of our sun. Quasars emit so much radiation that they outshine all other objects in the Universe. For this reason, quasars are very difficult to study - the emitted radiation does not allow these objects to be seen in detail.

On average, a quasar produces about 10 trillion times more energy per second than our Sun. The black hole inside the quasar sucks in absolutely everything that is within its reach. Cosmic dust, asteroids, comets, planets and even huge stars - all this becomes fuel for this giant.

Today it is very difficult to determine the exact number of discovered quasars, which is explained, on the one hand, by the constant discovery of new quasars, and on the other hand, by the lack of a clear boundary between quasars and other types of active galaxies. In 1987, 3,594 quasars were known. By 2005, this figure had increased to 195,000. The most distant quasars, due to their incredible luminosity, hundreds of times greater than the luminosity of ordinary galaxies, are recorded using radio telescopes at a distance of more than 12 billion light years. Recent observations have shown that most quasars are located near the centers of huge elliptical galaxies.

Quasars are compared to the lighthouses of the Universe. They are visible from vast distances and explore the structure and evolution of the Universe. The quasar's radiation spectrum represents all wavelengths measured by modern detectors, from radio waves to hard gamma radiation with a quantum energy of several teraelectronvolts. Quasars are usually surrounded by a ring of cosmic dust, and depending on its location, there are two types of quasars. The first type is when the ring is located so that it does not block the quasar from the observer. Quasars of the second type are protected from telescope lenses by the “wall” of the ring.

Not long ago, using a huge telescope in Chile, scientists were able to study one of the quasars, which belongs to the second type. They discovered that this quasar is surrounded by a nebula of ionized gas that extends over 590,000 light-years, about six times the diameter of the Milky Way. The nebula serves as a bridge connecting the quasar to a neighboring galaxy, and this fact can be considered as support for the hypothesis that quasars use nearby star clusters as “fuel”.

Scientists have suggested that quasar activity is caused by galaxy collisions. First, galaxies collide and their black holes merge into the universe. In this case, the black hole finds itself in the center of the dust cocoon formed as a result of the collision, and begins to intensively absorb matter. After about 100 million years, the glow from the hole's surroundings becomes so strong that emissions of radiation begin to break through the cocoon. As a result, a quasar appears. After another 100 million years, the process stops, and the central black hole begins to behave calmly again.
Just recently, scientists were able to photograph colliding quasars for the first time. As part of the work, scientists were interested in a double quasar, which is located at a distance of 4.6 billion light years from Earth in the constellation Virgo.

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

This story begins in 1960. Radio astronomers were improving their methods of pinpointing the location of radio sources. The radio source 3S48 seemed to coincide with one star, unlike any other: all the spectrum contained bright lines that could not be correlated with any of the known atoms. Then, in 1962, another mysterious star apparently coincided with another radio source, 3S 273.

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

Although the first of them were found by radio astronomers, only one tenth of the currently known quasars emit radio waves. In photographs they look like stars (meaning they are small compared to galaxies), but they all have a high redshift. The greatest redshift is almost 5. In this case, the wavelength of the light sent by the quasar is stretched by about 6 times. This distortion is much stronger than for most galaxies, although several exceptionally faint high-redshift galaxies have now been discovered using the largest telescopes.

Light from distant quasars reaches billions of miles away, so quasars tell us about conditions that existed in the Universe a long time ago.

Where are quasars located?

Most quasars have very high redshifts. Edwin Hubble showed how to use the redshift of a galaxy to determine its distance. Can we apply the same method to quasars? In other words, does the redshift of a quasar indicate its distance from us? According to many astronomers, this is true: 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. Firstly, in order to see them and our telescopes from such a huge distance, they must release an incredibly large amount of energy. Second, because their light takes billions of years to reach us, quasars can tell us about conditions that existed throughout the universe a long time ago. Astronomers want to find out what makes quasars glow so brightly, and by observing the most distant quasars, they 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 vast distances. In normal 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 the stars. Very detailed maps compiled by radio astronomers show that the vast majority of excess energy comes from the central regions of galaxies.

Black holes in galaxies

Now many are confident that the nuclei of energetically active galaxies harbor giant black holes. Probably their masses range from several thousand to several billion solar masses. The Hubble Space Telescope has detected whirlpools of matter orbiting black holes. Once a scooping hole has formed, it continues to grow larger by drawing in matter from surrounding areas. In giant galaxies like M87, the central black hole can consume the equivalent of several stars in a day.

The black hole and the surrounding disk 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 reserves. This could be gas blown off the surface of normal stars during their evolution, or it could be debris from a very large number of supernova explosions. As a black hole becomes more massive, the increasing 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 through nuclear fusion. This process converts energy into 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 is apparently not nuclear combustion 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 is bent.

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 reaching nine-tenths the speed of the estimate. To detect very distant objects, astronomers survey many, many faint objects. Using large optical telescopes, it is possible to obtain spectra of hundreds of such objects per night, which speeds up the search for quasars at high redshifts.

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

By observing distant galaxies, astronomers do something that historians cannot: astronomers can actually look back into the universe's past and see directly what conditions existed before, while historians use less than complete evidence from past times.

One reason why increasingly 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 have just begun to form.

Gravity creates lenses

Einstein's theory of gravity states that light, passing through a strong gravitational field, bends its trajectory. A famous test of this theory was carried out during a solar eclipse in 1919. The positions of 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 exhibit 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 located 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 light beam 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. Other times, a distant quasar blurs into a beautiful meadow of light. The visual illusion occurs because light from distant quasars passes through a cluster of galaxies on its way to Earth. If such a cluster contains densely concentrated mass - such as a giant black hole or a huge elliptical galaxy - then a distorted image appears.

From our house is the most powerful and deadly object in our entire Universe. A quasar is a dazzling beam of energy that spans several billion kilometers. Scientists cannot fully study this object.

What is a quasar

Today, astronomers around the world are trying to study quasars, their origin and principle of operation. Numerous studies prove that a quasar is a huge, endlessly moving cauldron of deadly gas. The object's most powerful source of energy is located inside, in the very heart of the quasar. This is a huge black hole. A quasar weighs as much as billions of suns.

Quasar absorbs everything that gets in his way. smashes entire stars and galaxies, sucking them into itself until they are completely erased and dissolved in it. Today, a quasar is the worst thing that can exist in the Universe.

Deep space objects

Quasars are the most distant and brightest objects in the Universe studied by mankind. In the 60s of the last century, scientists considered them radio stars, because they were discovered using the strongest source of radio waves. The term "quasar" comes from the phrase "quasi-stellar radio source." You can also find the name QSOs in numerous works of scientists about space. As the power of optical radio telescopes became much greater, astronomers discovered that a quasar is not a star, but a star-shaped object unknown to science.

It is assumed that the radio emission does not come from the quasar itself, but from the rays that surround it. Quasars are still one of the most mysterious objects that are located far beyond the boundaries of the Galaxy. Today, few people can talk about quasars. What it is and how they work can only be answered by the most experienced astronomers and scientists. The only thing that has been definitely proven is that quasars emit enormous amounts of energy. It is equal to that emitted by 3 million suns! Some quasars emit 100 times more energy than all the stars in our Galaxy combined. Interestingly, the quasar produces all of the above over an area approximately the size of the solar system.

Radiation and magnitude of quasars

Traces of previous galaxies have been found around quasars. They were recognized as redshifted objects that emit electromagnetic radiation along with radio waves and invisible light, and have very small angular dimensions. Before the discovery of quasars, these factors did not make it possible to distinguish their stars - point sources. On the contrary, extended sources are more likely to correspond to the shape of galaxies. For comparison, the average magnitude ratio of the brightest quasar is 12.6, and the average magnitude of the brightest star is 1.45.

Where are the mysterious celestial objects located?

Black holes, pulsars and quasars are quite far from us. They are the most distant celestial bodies in the Universe. Quasars have the greatest infrared radiation. Astronomers have the opportunity to determine the speed of movement of various objects, the distance between them and to them from the Earth.

If the quasar's radiation turns red, it means it is moving away from Earth. The greater the redness, the further away the quasar is from us and its speed increases. All types of quasars move at very high speeds, which in turn change endlessly. It has been proven that the speed of quasars reaches 240 thousand km/sec, which is almost 80%

We won't see modern quasars

Since these are the most distant objects from us, today we observe their movements that occurred billions of years ago. Since the light only managed to reach our Earth. Most likely, the most distant, and therefore the most ancient, are quasars. Space allows us to see them as they only appeared about 10 billion years ago. It can be assumed that some of them have ceased to exist today.

What are quasars

Although this phenomenon has not been studied enough, according to preliminary data, a quasar is a huge black hole. Its matter accelerates as the hole's vortex sucks in matter, causing these particles to heat up, rub against each other, and cause the total mass of matter to move endlessly. The speed of the quasar molecules becomes faster every second, and the temperature gets higher. The strong friction of particles causes the release of a huge amount of light and others, such as x-rays. Every year, black holes can absorb the mass of one of our Sun. As soon as the mass drawn into the death funnel is absorbed, the released energy will spread out as radiation in two directions: along the south and north poles of the quasar. Astronomers call this unusual phenomenon a “spaceplane.”

Recent observations by astronomers show that these celestial objects are mainly located in the center of elliptical galaxies. According to one theory of the origin of quasars, they represent a young galaxy in which a massive black hole absorbs the matter surrounding it. The founders of the theory say that the source of radiation is the accretion disk of this hole. It is located in the center of the galaxy, and from this it follows that the spectral red shift of quasars is greater than the cosmological one by exactly the amount of gravitational shift. This was previously predicted by Einstein in his general theory of relativity.

Quasars are often compared to the beacons of the Universe. They can be seen from the longest distances, thanks to them their evolution and structure are studied. Using a “celestial beacon”, the distribution of any substance along the line of sight is studied. Namely: the strongest spectral absorption lines of hydrogen are transformed into lines along the absorption redshift.

Versions of scientists about quasars

There is another scheme. A quasar, according to some scientists, is a young galaxy in the making. The evolution of galaxies is little studied, since humanity is much younger than them. Perhaps quasars are an early state of galaxy formation. It can be assumed that the release of their energy comes from the youngest nuclei of active new galaxies.

Other astronomers even consider quasars to be points in space where new matter in the Universe originates. Their hypothesis proves the complete opposite of a black hole. Humanity will need a lot of time to study the stigmata of quasars.

Famous quasars

The first quasar to be discovered was discovered by Matthews and Sandage in 1960. It was located in the constellation Virgo. Most likely, it is associated with 16 stars of this constellation. After three years, Matthews noticed that the object had a huge spectral redshift. The only factor proving that it was not a star was its release of a large amount of energy in a relatively small area of ​​​​space.

Observations of humanity

The history of quasars began with the study and measurement of the visible angular sizes of radioactive sources using a special program.

In 1963, there were already about 5 quasars. In the same year, Dutch astronomers proved the spectral shift of lines towards the red spectrum. They proved that this was due to cosmological displacement as a result of their removal, so the distance could be calculated using Hubble's law. Almost immediately, two more scientists, Yu. Efremov, discovered the variability of the brightness of the discovered quasars. Thanks to photometric images, they established that the variability has a periodicity of only a few days.

One of the closest quasars to us (3C 273) has a redshift and brightness corresponding to a distance of approximately 3 billion. light years. The most distant celestial objects are hundreds of times brighter than ordinary galaxies. They can be easily detected using modern radio telescopes at a distance of 12 billion light years or more. A new quasar was recently detected at a distance of 13.5 billion light years from Earth.

It is difficult to calculate exactly how many quasars have been discovered to date. This is due both to the constant discovery of new objects and to the lack of a clear boundary between active galaxies and quasars. In 1987, a list of registered quasars was published in the amount of 3594, in 2005 there were more than 195 thousand, and today their number has exceeded 200 thousand.

Initially, the term “quasar” denoted a certain class of objects that, in the visible (optical) range, are very similar to a star. But they have a number of differences: very strong radio emission and small angular dimensions (< 10 0).

This initial idea of ​​these bodies developed at the time of their discoveries. And it is still true, but still scientists have recognized radio-quiet quasars. They don't create as much radiation. As of 2015, about 90% of all known objects were registered.

Today, the stigmata of quasars are determined by the red shift of the spectrum. If a body is discovered in space that has a similar displacement and emits a powerful flow of energy, then it has every chance of being called a “quasar.”

Conclusion

Today, astronomers count about two thousand such celestial bodies. The main instrument for studying quasars is the Hubble Space Telescope. Since the technological progress of mankind cannot but delight us with its successes, we can assume that in the future we will solve the riddle of what a quasar and a black hole are. Perhaps they are a kind of “garbage box” that absorbs all unnecessary objects, or maybe they are the centers and energy of the Universe.

In 1963, a discovery of exceptional importance was made: quasars were discovered - objects whose light (and radio waves) took as much as 15 billion years to reach us. This means that now we see them as they were shortly after the Big Bang, as a result of which the history of our Universe began.

What are quasars? First of all, these are sources of radio waves. Hence their name: quasi (that is, almost) stellar radio sources. Quasars amazed everyone, first of all, with their colossal power: being at the very “edge” of the Universe, they emitted such intense radiation that it not only reached us, although it was in transit for more than 10 billion years, but it reached it very intense. After all, a quasar can be observed with the simplest 20-centimeter telescope, while to observe objects located thousands of times closer, five-meter telescopes are needed! A quasar emits such a huge amount of energy that a legitimate question arises where it gets it from. The energy it emits in half an hour is equal to all the energy released during a Supernova explosion! The luminosity of each quasar is a thousand times higher than the luminosity of large galaxies, which include billions of stars! Another striking thing about the quasar is the compactness of this energy factory. A quasar is more comparable in size to a star than to a galaxy. (That’s why it was called a “quasi” stellar source. Naturally, the main question is how the quasar works, how its energy factory works, or, as physicists say, what its physical nature is. No less amazing is the fact that its energy factory works irregularly. The energy emitted by a quasar (it emits visible light, ultraviolet, infrared and x-rays, radio waves) changes not only over several years, but also over several months or even weeks. This is with an average age of 10 million years! then explain such significant disruptions in the work of quasar energy engineers. For example, the quasar 345 in three weeks changed its luminosity by half, and the quasar number 466 in the same third Cambridge catalog (CS) changed its luminosity by half even within a few days (in over the course of several months, its luminosity changed 20 times!) Such changes are characteristic not only of the visible luminosity, but also of the intensity of the radio emission of the quasar.

Please note that we are now receiving information about those quasars that existed about 10 billion years ago. Having existed for only 10 million years, they ceased to be quasars. Thus, we are talking about objects that existed in the Universe before the Earth was formed. This time shift (the ability to travel into the past and the inability to see what is now happening in its distant corners) occurs because it can take billions of years to transmit information using light in the Universe! Therefore, those quasars that emit now can be observed in 10 billion years, when their radiation comes to us.

Measurements have shown that quasars move (or rather, moved) at speeds that are 87% of the speed of light. The velocities of quasars are directed away from us, that is, they fly away in all directions at enormous speeds. It was not the speeds that were measured, but the frequency shift of quasar radiation due to the Doppler effect. It turned out that the shift of the emission lines of hydrogen atoms occurs towards the red end of the spectrum, that is, the emission frequency increases, which occurs as the source moves away. Quasars move at speeds exceeding 250,000 km/s! Such speeds are prohibited for other objects. So, if the star had a speed of more than 1000 km/s, then it would leave its galaxy. In addition, stars move both away from us and towards us. Quasars move exclusively away from us.

How does a quasar work9

Astrophysicists have been studying this question for a long time. The most difficult thing was to understand where the quasar gets such a large amount of energy from. During this time, many hypotheses were proposed to explain the structure of the quasar. But they turned out to be untenable. Therefore, there is no point in considering them.

It turned out that the problem of quasars is related to the problem of active galactic nuclei. They were discovered back in 1943 by the American astronomer K. Seyfert. In the spectra of radiation coming from space objects, wide (“blurred”) and very intense lines of hydrogen, nitrogen, oxygen and other chemical elements were discovered. The position of the radiation line, which corresponds to a certain frequency (and therefore wavelength), depends on the speed of the emitting particle and where this speed is directed. If the speed of the emitter is directed towards us, then the line shifts in one direction, and if it is away from us, then in the opposite direction. The movement of the emitter across the line of sight does not lead to a shift in the line in the emission spectrum. If radiation from particles is simultaneously measured, some of which are moving towards us, and the other part is moving away from us, then the radiation line expands in both directions. The higher the particle speed, the wider the emission lines become. Based on the magnitude of this broadening, the speed of particle movement can be calculated. This was done by K. Seifert. He found that in the active nuclei of galaxies, gas particles move at enormous speeds, reaching tens of thousands of kilometers per second. Gas velocities in ordinary galaxies are no more than 300 km/s. The speeds of movement of gas particles in active galactic nuclei are comparable in magnitude to the speeds of particle expansion during supernova explosions. Seyfert examined the active nuclei of 12 of these unusual galaxies. These galaxies were subsequently called Seyfert galaxies.

The nuclei of Seyfert galaxies resemble quasars in their radiation, but their radiation power is less. They are also called mini-quasars. The radiation from active nuclei of Seyfert galaxies, like the radiation from quasars, is variable. It was concluded that quasars are central objects (nuclei) within galaxies. Further studies of quasars showed that the processes responsible for the release of energy are not limited to the galactic core, but are the result of the interaction of the galaxy with this core.

QUASI-STELLAR RADIO SOURCES

When radio astronomy was still taking its first steps, the term “radio stars” became widespread. This is what some “point” sources of cosmic radio emission were called. Gradually, many of them were identified with nebulae and galaxies already discovered by astronomers. Almost everything, but still not everything.

By 1963, five star-shaped objects remained mysterious, which were later called quasi-stellar radio sources, or quasars.

Judging by the power of radio emission, quasars cannot possibly be stars in the usual, generally accepted sense of the word. Five objects listed in the 1963 star catalogs (included in the 3rd Cambridge Catalog (3C) of cosmic radio sources) under the symbols 3C48 (identified with the 16th magnitude star in the constellation Triangulum), 3C147, 3C196, 3C273 (identified with the star 13th magnitude in the constellation Virgo) and 3C286.

Quasars can either be the most distant objects known to us and the most powerful sources of radiation, or satellites of fairly ordinary galaxies and then their radiation cannot be explained using known mechanisms.

Not all quasars are radio sources

Although we owe the discovery of quasars to radio astronomy, it soon became clear that not all of them are radio sources. A large number of non-radio-emitting objects were discovered, which in all other respects were similar to the first quasars 3C273 and 3C48. Of the more than 1,300 known quasars, only a few percent are radio sources. Thus, most quasars are “quiet” in the radio range.

QUASARS – THE MOST AMAZING MYSTERY OF ASTROPHYSICS

The name “quasars” is an abbreviation for the term “quasi-stellar radio sources.” But since many quasars turned out to have no noticeable radio emission, they began to be called “quasi-stellar objects.” However, the short name “quasars” is now widely used.

At first it seemed that these celestial bodies were unlike anything else and combined incompatible properties. It took a lot of effort before it was realized that quasars are related to radio galaxies and other galaxies in whose nuclei powerful processes of energy release occur. In quasars these processes reach their maximum scale and intensity. The radiation power of a quasar is hundreds of times greater than that of the Galaxy, and this radiation is generated in a volume comparable in size to the volume of the Solar System. A quasar is a very compact object.

The discovery of quasars and the first two decades of their study are, apparently, only the beginning of long-term research, the purpose of which is to explain the physical mechanism of the activity of galactic nuclei and quasars. They still remain the most amazing mystery of modern astrophysics.

Distance to quasars

As observational data accumulates, most astronomers have come to the conclusion that quasars are farther from us than any other observable object. But a small number of astronomers argued that the most convincing observational evidence suggests the spatial proximity of quasars and not very distant galaxies.

RED SHIFT

Most quasars emit radio waves intensely. When astronomers pinpointed the positions of these radio sources in visible light photographs, they discovered star-shaped objects.

To establish the nature of strange celestial bodies, their spectrum was photographed. And we saw something completely unexpected! These “stars” had a spectrum that was sharply different from all other stars. The spectra were completely unfamiliar. For most quasars, not only did they not contain the well-known lines of hydrogen that are characteristic of ordinary stars, but at first glance it was impossible to detect even a single line of any other chemical element in them. The young Dutch astrophysicist M. Schmidt, who worked in the USA, found out that the lines in the spectra of strange sources are unrecognizable only because they are strongly shifted to the red region of the spectrum, but in fact these are lines of well-known chemical elements (primarily hydrogen).

The reason for the shift of spectral lines of quasars has been the subject of great scientific debate, as a result of which the vast majority of astrophysicists have come to the conclusion that the red shift of spectral lines is associated with the general expansion of the Metagalaxy.

In the spectrum of objects 3C273 and 3C48, the redshift reaches an unprecedented value. A shift of lines towards the red end of the spectrum may be a sign that the source is moving away from the observer. The faster a light source moves away, the greater the red shift in its spectrum.

It is characteristic that in the spectrum of almost all galaxies (and for distant galaxies this rule has not a single exception) the lines in the spectrum are always shifted towards its red end. Roughly speaking, the redshift is proportional to the distance to the galaxy. This is precisely what expresses the LAW OF RED SHIFT, which is now explained as the result of the rapid expansion of the entire observable set of galaxies.

Removal speed

The most distant galaxies known so far have a very large redshift. The corresponding removal velocities are measured in tens of thousands of kilometers per second. But the redshift of object 3C48 exceeded all records. It turned out that it is carried away from the Earth at a speed of only about half the speed of light! If we assume that this object obeys the general law of redshift, it is easy to calculate that the distance from Earth to object 3C48 is 3.78 billion light years! For example, in 8 1/3 minutes a ray of light will reach the Sun, and in 4 years it will reach the nearest star. And here there are almost 4 billion years of continuous super-fast flight - a time comparable to the lifespan of our planet.

For object 3C196, the distance, also found from the redshift, turned out to be equal to 12 billion light years, i.e. we caught a ray of light that was sent to us even when neither the Earth nor the Sun existed! Object 3S196 is very fast - its receding speed along the line of sight reaches 200 thousand kilometers per second.

Age of quasars

According to modern estimates, the ages of quasars are measured in billions of years. During this time, each quasar emits enormous energy. We do not know the processes that could cause such energy release. If we assume that we have a superstar in front of us, in which hydrogen “burns,” then its mass should be a billion times greater than the mass of the Sun. Meanwhile, modern theoretical astrophysics proves that with a mass more than 100 times that of the sun, a star inevitably loses stability and breaks up into a number of fragments.

Of the currently known quasars, the total number of which is more than 10,000, the closest is 260,000,000 light years away, the most distant is 15 billion light years away. Quasars are perhaps the oldest of the objects observed by us, because. From a distance of billions of light years, ordinary galaxies are not visible to any telescope. However, this “living past” is still completely incomprehensible to us. The nature of quasars is still not fully understood.

EXTRAORDINARY LUMINITY

Subject to the same law of cosmological distance as galaxies, the sources 3C273 and 3C48 are themselves very different from ordinary galaxies like our Galaxy. What is most striking is their extraordinary luminosity, hundreds of times greater than the luminosity of our Galaxy.

It would seem that objects so far from Earth should only be accessible to an observer armed with the most powerful modern telescopes. In fact, for example, object 3C273 can be found in the constellation Coma Berenices as a 12.6 magnitude star. Such stars are accessible even to amateur telescopes.

Another mysterious fact is that quasars are clearly smaller in size than galaxies: after all, they look like point sources of light, while even the most distant galaxies look like blurry luminous blots.

Energy source

How monstrous in radiation power these light sources must be if from a distance of billions of light years they seem so bright!

The most difficult question associated with quasars is to explain the gigantic release of energy. If quasars are indeed located at cosmologically large distances from us (i.e., the red shift is really associated with the expansion of the Universe), then it is necessary to explain how this strongest luminosity arises. It remains a mystery what kind of energy source keeps the quasar glowing. One thing is clear that whatever this source is, it is concentrated in a relatively small region of space, that is, it is quite compact. And this in itself already suggests that the mechanism of energy release in a quasar is very unusual.

Many astrophysicists believe that quasars are associated with the nuclei of galaxies that are at a certain stage of evolution. For example, the core of the M87 galaxy is much brighter than its outer parts. But there are galaxies of other types, the so-called Seyfert galaxies, in which the contrast of the bright core with the faintly luminous rest is even more pronounced. Perhaps quasars are the next step in this sequence. If they are located very far away, then we see only their bright core, while the weak shell (if there is one at all) is simply not visible at all.

It is also suggested that, as in the M87 galaxy, the release of energy in quasars may be associated with the presence of supermassive black holes. Since the mid-1970s, the idea that the enormous release of energy in quasars is explained by black holes has gained great popularity.

The process of energy release is also associated with the work of gravitational forces, and the radio emission of a quasar is synchrotron radiation of charged particles in a magnetic field.

Some astronomers believe that the energy fluxes from quasars are much lower because the distances to them are greatly exaggerated. If quasars are, say, 100 times closer to us than we think, then we overestimate their luminosity by 10,000 times when calculating the emission power from their observed brightness. Astronomers who hold this view rely on the fact that quasars are often visible in the sky near peculiar galaxies. These galaxies, although somewhat unusual in their structure, have normal redshifts corresponding to receding velocities of a few percent of the speed of light. And quasars located in the sky near them have redshifts 10 - 20 times greater!

If quasars are located in the vicinity of fairly nearby galaxies, how can we explain their huge redshifts? The only reasonable explanation is the Doppler effect, but why do we always only see a redshift (moving away) and never a violet shift (approaching)? And how could matter be ejected (always away from us!) at such enormous speeds and still retain the shape of a single object?

The answer is: no one knows. For 15 years, it was not possible to determine either the distance to quasars, or their nature and the sources of their colossal energy. Perhaps the mystery of quasars contains the key to some new field of astrophysics, some new possibilities for the occurrence of large redshifts in situations unknown to us, or new ways of generating gigantic energies if quasars are very far away. Let's hope that in the coming years we will be able to overcome these difficulties in explaining the nature of the distant regions of the Universe in which quasi-stellar objects are located. And now we can only say: apparently, these are natural and not artificial astronomical objects, since it is not yet clear how civilization could “make” a quasar.

VARIABILITY AND SIZE

Another mystery of quasars is that some of them change their brightness over periods of several days, weeks or years, while ordinary galaxies do not show such variations.

Moscow astronomers A.S. Sharov and Yu.N. Efremov decided to find out how “strange stars” behaved in the past. They carefully looked through 73 negatives that showed object 3C273 from 1896 to 1963. The conclusion reached by Soviet scientists can be considered quite reliable. And he is amazing. It turned out that 3C273 changed its brightness! And not just a little, but very noticeably - from 12.0 to 12.7 magnitude, i.e. almost twice. There were cases (for example, in the period from 1927 to 1929) when, over a short period of time, the radiation flux from 3C273 increased by 3–4 times! Sometimes in a few days the object changed by 0.2 - 0.3 magnitude. At the same time, externally, optically, no other significant changes occurred - the “strange star” invariably seemed to be a star, albeit a variable one. A similar phenomenon was later discovered in object 3S48.

Thousands of variable stars are known, changing for various reasons. But among ordinary galaxies, not a single variable was recorded. Although many of them contain thousands and millions of variable stars, fluctuations in their luminosity occur widely and are so insignificant for the galaxy as a whole that the total radiation of galaxies always remains practically unchanged. Not a single optical instrument in the world can detect even the slightest fluctuations in the luminosity of any galaxy.

Three possibilities remain. The first of them is absurd: the stars of the galaxy change immediately and in the same way, as if on command, in the same rhythm. From the physical side, such an explanation is so absurd, so contrary to all our knowledge of the cosmos, that it does not deserve serious consideration. The second possibility is that strange objects, similar to galaxies in the nature of their redshift, have a physical nature completely different from galaxies. However, most astronomers assume that quasars are the active nuclei of ultra-distant galaxies.

It is indisputable that quasars are not extended star systems scattered over tens of thousands of light years, but some very compact bodies of relatively small size and colossal mass (billions of solar masses). Relatively small sizes can explain the rapidity of fluctuations in the luminosity of the entire object as a whole, and the huge mass is the only possible reason for the exceptional brightness, or more precisely, the luminosity of the celestial body. The more massive the star, the brighter it shines. This pattern follows both from observations and from theoretical considerations.

Not only in mass, but also in radiation power, quasars differ sharply from all known celestial bodies. Even supernovas pale in comparison. Supernovae emit several billion times more light than the Sun just at the moment of their powerful explosion. An ordinary quasar always emits tens of thousands of times more

Infrared and X-ray emissions from quasars

In recent years, astronomers have been able to detect infrared and X-ray emissions from quasars; They discovered that the emission power of some objects in these regions of the spectrum is even greater than in the visible region and radio range. If we add up the radiation energies in all regions of the spectrum, it turns out that some quasars generate 100,000 times more energy per second than giant galaxies, provided that our estimates of the distances to quasars are correct.

The development of X-ray astronomy has helped to establish that most quasars turned out to be powerful X-ray sources. Some hint of this could be seen as a result of the very first X-ray observations of the quasar 3C273, and in the latest studies of the Einstein Observatory (NEAO-B), more than 100 quasars with strong X-ray emission were discovered.

Based on these observations, it is believed that, unlike radio emission, X-ray emission is a characteristic property of quasars.

GALAXIES AND QUASARS

Recently, a lot of evidence has accumulated that quasars are related to galaxies and are vast star systems with compact central regions - nuclei, from where the bulk of their radiation comes. The sizes of the nuclei are small, their brightness is much higher than the brightness of stars, so quasars look like point sources in astronomical photographs.

Perhaps the first of the facts that made it possible to find the place of quasars in the general family of astronomical systems was the chemical composition of their emitting regions: they emit lines of the same chemical elements as the Sun or clouds of gas in the disk of our Galaxy. The “normal” chemical composition of quasars directly indicates their relationship with “ordinary” star systems.

It is very important that in parallel with the study of quasars, an in-depth study of galaxies continued. This made it possible to establish that a large redshift is not the exclusive privilege of quasars. It was also discovered in the galaxy 3C295, which also exhibits increased radio emission and is included in the 3rd Cambridge catalogue. This redshift is even greater than that of the first two quasars, 3C273 and 3C48. The highest redshift recorded for galaxies belongs to galaxy 3C324 from the same catalogue. Methods for observing galaxies at such high redshifts, applied to quasars, made it possible to directly detect extended luminous formations around the closest ones, which turned out to be star systems similar to ordinary galaxies. In 1982, it was possible to observe a stellar system around the core of the quasar 3C273.

There is also a deep relationship in the manifestations of activity of galactic nuclei and quasars. Significant similarities are revealed between radio-emitting quasars and radio galaxies, i.e. galaxies with increased radio emission.

Quasar cores and galaxy cores

Active processes in galactic nuclei became the subject of comprehensive study shortly before the discovery of quasars, since 1955, when I.S. Shklovsky explained the phenomenon of ejection from the nucleus of the Virgo galaxy. A.V.A. Ambartsumyan put forward a general concept of the activity of galactic nuclei and attracted the phenomenon received widespread attention from astronomers. Various manifestations of nuclear activity - variability, outflows and ejections of matter, radio-emitting components - reach maximum scales in energy and spatial dimensions in quasars. The reservoir and energy generator for these phenomena is the quasar core, which should be more massive and much more compact than the most powerful galactic nuclei.

Back in the 60s, Soviet astrophysicist B.V. Comberg hypothesized that quasars (like the nuclei of active galaxies) are supermassive binary systems. This hypothesis, which has received a number of confirmations in recent years, requires new observations. Most likely, the cores of quasars are not stars, nor simple clusters of them, but compact and very massive objects, which are the cores of extremely active galaxies, billions of light years away from us and therefore invisible from great distances. This is confirmed, for example, by the discovery of a luminous halo around the quasar 3C273, which is usually considered as evidence that this quasar is a distant galaxy.

The similarity of emissions from quasar 3C273 and the Virgo A galaxy is an important indication of the general nature of activity phenomena in quasars and galactic nuclei. Equally important, many massive elliptical galaxies are sources of intense radio emission. Such, for example, is the Cygnus A galaxy. Its radio emission was discovered by chance in 1946. In terms of radiation power, the Cygnus A radio galaxy is comparable to the quasars 3C273 and 3C48, although it is inferior to the most powerful quasars, whose luminosity is still 100 - 1000 times greater.

Quasars and Seyfert galaxies

Seyfert galaxies, named after the American astronomer K. Seyfert who discovered them in the 40s, also have a significant resemblance to quasars. They belong to the class of spiral galaxies and make up about one hundredth of their total number. Seyfert galaxies have compact, bright nuclei that emit radiation in highly expanded hydrogen and helium lines. Nuclei are sometimes a powerful source of radio waves and X-rays. Their radiation is variable, which, as in the case of quasars, indicates violent processes occurring in the cores of these galaxies.

Quasars and Lacertids

The so-called lacertids are also related to quasars (from Lacerta - the Latin name for the constellation Lizard, where the first object of this type was found - the BL Lizard galaxy). These are strong sources of optical, infrared and radio radiation. Like quasar cores, they appear in photographs as point sources surrounded by sometimes faintly glowing halos that are actually star systems. Lacertids also show strong variability. The distances to them are comparable to the distances to distant quasars.

From normal galaxies to quasars

So, there is a very obvious continuity of properties from normal galaxies - through radio galaxies, elliptical galaxies with active nuclei, Seyfert galaxies and lacertides - to quasars. Clarification of this fact was a decisive step towards understanding the nature of quasars.

Quasars and our Galaxy

The core of our Galaxy is not active. Its central region cannot be observed by optical methods due to the absorption of light by gas and dust clouds lying on the line of sight. Data about it are obtained from observations in the infrared and radio ranges of electromagnetic waves, for which clouds are transparent. At the center of the Galaxy's rotation is a fairly bright radio source, Sagittarius A; its radio luminosity is much lower than that of quasars and active nuclei.

MULTIPLE QUASARS

Particular attention of astrophysicists and physicists was attracted by multiple (double, triple) quasars: a double quasar in the constellation Ursa Major (1978), a triple quasar in the constellation Leo (1980) and the same quasar in the constellation Pisces (1981). Each of the objects were twin quasars located at a distance of several arcseconds from each other, having very similar spectra and redshifts. However, in all likelihood, the listed quasars are not “true” multiple quasars, but only images of the corresponding source. The splitting of one image into several occurs under the influence of the gravitational field of a massive galaxy that finds itself on the path between the quasar and us. Light rays from quasars can be bent by the gravity of galaxies that act as sources of gravitational focusing. Such gravitational lenses can distort the shapes of distant galaxies, which, according to some scientists, opens up new opportunities for studying large-scale inhomogeneities in the distribution of matter in the Universe.

It is possible that the gravitational lens effect in some cases is created not by distant galaxies, but by massive black holes. Indian astrophysicists G. Padmanabhan and S. Chitre drew attention to cases when a double image of a quasar is visible, but the galaxy that caused this phenomenon was not found nearby. So a hypothesis emerged that the effect is created by almost point-like black holes with a mass a million times greater than the mass of the Sun. Since so far not a single black hole has been discovered anywhere, it is difficult to say how close to the truth such a hypothesis is.

The question of whether “true” double quasars exist in nature remains a subject of research and debate.

Quasar(English) quasar) is a particularly powerful and distant active galactic nucleus. Quasars are among the brightest objects in the Universe. The radiation power of a quasar is sometimes tens and hundreds of times higher than the total power of all the stars in galaxies like ours.

Quasars were initially identified as high redshift objects ( redshift- shift of the spectral lines of chemical elements to the red (long-wave) side) and electromagnetic radiation, having very small angular dimensions. For this reason, they could not be distinguished from stars for a long time, because extended sources are more consistent with galaxies. It was only later that traces of parent galaxies were discovered around quasars.

Term quasar stands for "star-like". According to one theory, quasars are galaxies at the initial stage of development, in which a supermassive black hole absorbs surrounding matter.

The first quasar, 3C 48, was discovered in the late 1950s by Alan Sandage and Thomas Matthews during a radio sky survey. In 1963, 5 quasars were already known. In the same year, Dutch astronomer Martin Schmidt proved that the lines in the spectra of quasars are strongly redshifted.

Recently, it has been accepted that the source of radiation is the accretion disk of a supermassive black hole located in the center of the galaxy and, therefore, the red shift of quasars is greater than the cosmological one by the amount of gravitational shift predicted by A. Einstein in the general theory of relativity (GTR). To date, more than 200,000 quasars have been discovered. The distance to it is determined by the redshift and brightness of the quasar. For example, one of the closest quasars and the brighter one, 3C 273, is located at a distance about 3 billion light years. Recent observations show that most quasars are located near the centers of huge elliptical galaxies, and the irregular variability of quasar brightness on time scales of less than a day indicates that region of generation of their radiation has a small size comparable to the size of the solar system.

On average, a quasar produces about 10 trillion times more energy per second than our Sun (and a million times more energy than the most powerful known star), and exhibits emission variability across all wavelength ranges.

The physical mechanism responsible for the generation of such powerful radiation in a relatively small volume is not yet reliably known. The processes occurring in quasars are the subject of intensive theoretical research.

Narrow absorption lines of hydrogen and ions of heavy elements were discovered in the spectra of distant quasars. The nature of the narrow absorption lines remains unclear. The absorbing medium can be extensive coronas of galaxies or individual clouds of cold gas in intergalactic space. It is possible that such clouds may be remnants of the diffuse medium from which galaxies were formed.