Cosmic rays. Cosmic rays: composition and origin. Modulation effects in cosmic rays

Cosmic rays

What are cosmic rays?

Traveling through the endless expanses of the universe, meeting many surprises and all sorts of external influences on its way. And one of these influences turns out to be rays from space.
Cosmic rays - these are particles with and without a charge, arriving from the universal spaces to the surface of the Earth, lingering in the air shell of our planet. Cosmic ray physics has become an area with a very promising future. Because by studying cosm rays, scientists can better understand the processes taking place in Stars , in our and not only Galaxies ... Such tremendous opportunities will be able to provide us cosmic rays .

Cosmic ray physics and history of discovery

Cosmic rays became known by chance in 1900 d. when measuring the amount of ionization and electrical conductivity of the gas, by means of electroscopes. German physicists Julius Elster and Hans Geitel autonomously from each other, they made the discovery of an unknown natural origin of air ionization.

Scottish physicist Charles Wilson while in Britain and working with ionization chamber , concluded that the incoming radiation has an extraterrestrial cause. With the help of a shielded camera, Wilson found out that the penetrating property of unfamiliar radiation is stronger than that of X-ray and gamma rays, and gave the name to it ultra-gamma ionization .

Sorry, follow-up study cosmic rays slightly slowed down the process of studying physics in this area. Ernest Rutherford , at the same time, made many experiments on the protection of the detector with lead and gave an explanation for this, as the gamma-activity of the construction material. Later, the most sensitive electrometer gave results that showed that ionization was done less over reservoirs and it was assumed that this ionization is a consequence of the radioactivity of the lithosphere in the gamma spectrum. It seems to me that it's very funny - what came from space interpreted as if the source was in the ground.
For a very long time, scientists have been collecting experimental data. They experimented both directly on the ground and at altitude, for example, on the Eiffel Tower and on a balloon. And after 25 years, in 25 -th year of the last century, a scientist physicist Robert Millikan from America carried out a number of measurements of water absorption of high-altitude radiation in water bodies located at an altitude 3.6 and about 2 -x km. As a result of measurements, it turned out that radiation pointing down through the air.
Millikan calls this phenomenon for the first time cosmic rays ... This will be seen as a real breakthrough in the study of this phenomenon. But still, origin of cosm rays the scientists did not understand. A huge contribution to the understanding of rays was made by a Soviet physicist Dmitry Skobeltsin ... He, through experiments, he established that cosmic rays these are particles that have an electric charge and cause in the air showers particles. Subsequently shower theory these particles are studied by a physicist Lev Landau .
V 36 year of the last century Victor Hess awarded the Nobel Prize for identifying cosmic rays . 24 years passed before they realized the fundamental value of this phenomenon. By that time it was already clear that cosmic rays these are, in most cases, particles with a positive charge and very high energy.
Study period from 30 -x to 55 -s, became an era fundamental particles v cosmic rays ... At that time, they discovered step by step: positrons, muons, bi-mesons etc. The more powerful the accelerators became, the higher the active energy range in physics rose, which made it possible to study in detail the phenomena in cosmic rays ... However, the upper energy limits, which in cosmic rays are now 3x10 20 electron volts, as before, are an order of magnitude superior to the results embodied in laboratories.

For example, to understand superiority: in TANK (Large Hadron Collider) particles are accelerated to an energy of 14x10 12 degree electron-volts, which is about 10 million times less. By the way, remember the time period when you said that TANK will cause black holes, which will lead to the death of humanity. As follows from the above, in the atmosphere for a very long time there have been events energetically more powerful than those created in TANK ... And this did not interfere with the development of mankind. Cosm rays as if they are “ natural accelerators«.
Obviously, most cosmic rays arrives to us from Suns ... But in 1960 year V.L. Ginzburg and S. I. Syrovatsky expressed the view that cosmic rays are born in the galaxy during supernova explosions. And already after 8 years, high energy gamma rays from the galaxy are detected. Subsequently, the theories of scientists were developed for consideration extragalactic footprints cosmic rays and particles from the young universe.
Enough cosmic ray history , let's discuss from what are cosm rays .

Cosmic ray composition and origin

As mentioned earlier, through cosmic rays , experimentally recorded such particles as positron, muon, bi-meson ... However, the composition cosmic rays these particles are extremely few. Most cosmic rays make up protons , it's about 90% from all rays coming from space. About 7% make up alpha particles , i.e. helium nuclei , and only a small part about 1% these kernels are an order of magnitude heavier, for example, carbon and iron ... Surprisingly, these "heavy" nuclei arrive precisely from galaxies .
Cosmic rays arriving from our stars have a composition, in most cases, these are protons 98% ... What cosmic rays from the galaxy consist of heavy nuclei, it is elementary that they are born as a result of the formation (explosion) supernovae .
By the way, cosmic rays confirmed THEN (Theory of Relativity ). Which makes it even more important cosmic rays .
When proton interacts with the earth's atmosphere, arises shower of particles ... Let us consider this phenomenon in more detail. When exposed cosmic rays to atomic nuclei of air gases, in most cases with nuclei N 2 and O 2 , primary cosmic rays , as a rule, give birth to a huge number of secondary particles ions, protons, neutrons, muons, electrons, positrons and photons ... This stream has a huge area and bears the name of the big air shower ... For one interaction, the proton, as a rule, gives up about half of its energy potential. As a result of this act are born in most cases peonies ... Each next act of the primary particle creates a stream of new particles that adhere to the trajectory of the primary particle, creating shower ... Created by peonies usually affect the atomic nuclei of the air, but they can also be destroyed, creating muonic and electron-photon flow components. As a result, the nuclei of the particle do not eventually reach the ground by "reincarnating" into muons, neutrinos and gamma quanta .

Cosmic ray detection

How are rays from space detected and what data do scientists want to get from this phenomenon?

Because energy spectrum cosmic rays huge from 10 6 before 10 20 electron-volt , the methods of their detection and monitoring are extremely diverse. For example, these are ground structures of a huge territory for detecting large air cascades ( showers ). These structures can detect traces cosmic rays , and a wide part of the sky is observed. These detectors are capable of working more than 90% time. Unfortunately, these structures are very sensitive to background radiation , and sometimes it is very difficult to distinguish between particles arriving from space and terrestrial particles.

Cherenkov radiation
Another way to register is to use Cherenkov radiation ... When certain particles, such as cosmic particles, move faster speed of light in some environment, appears radiation called Cherenkovsky , which is detected. These telescopes, although they can perfectly distinguish between background radioactivity and cosmic rays , but they function only in clear night weather, when there is no moon in the sky and they have a tiny field of view. And such telescopes can be investigated for a short time.

Veritas telescope
The most popular telescope for recording Cherenkov radiation is Veritas and Has ... Telescopes detect gamma radiation , i.e. cherenkovskoe. They were able to make an enormous contribution to the study of pulsars, quasars, star clusters, gamma-ray bursts, and to the study origin of cosm rays outside the galaxy and the supermassive black hole that is the center of the Milky Way.
There are other ways to register cosmic rays , as well as the consequences caused by them, but they all have a connection only with their effect with some materials, be it plastic, nitrogen or supersaturated water vapor, etc.

The use of cosm rays

Is there a practical application of cosmic rays ?!

Egyptian pyramids
Definitely yes. For example, researching structures Egyptian pyramids ... In the process of exposure cosmic rays on the atmosphere, as noted above, appear muons ... And with the help muon radiography or as it says in "Natural" , scientists were able to "see" still unexplored voids in the pyramids. In general, this suggests that today's fundamental particle physics and cosmic rays , will be able to make new discoveries in archeology.

Neutrino
But let's take a closer look at this phenomenon. Actually, cosmic rays are the sources of these "elusive" neutrino exciting the scientific world. Most likely, cosmic rays can give us information about such " theoretical»Particles like magneto-monopoles or gravitons , which we are not yet able to investigate, due to the inability to create the necessary conditions with our modern accelerators. Besides, relict radiation this is one of the varieties cosmic rays ... And the northern lights are also a consequence of the manifestation cosmic rays .

Cosmic rays (radiation) are particles that fill interstellar space and constantly bombard the Earth. They were discovered in 1912 by the Austrian physicist Hess using an ionization chamber in a balloon. The maximum energies of cosmic rays are 10 21 eV, i.e. are many orders of magnitude higher than the energies available to modern accelerators (10 12 eV). Therefore, the study of cosmic rays plays an important role not only in the physics of space, but also in the physics of elementary particles. A number of elementary particles were first discovered precisely in cosmic rays (positron - Anderson, 1932; muon () - Neddermeier and Anderson, 1937; pion () - Powell, 1947). Although cosmic rays include not only charged, but also neutral particles (especially a lot of photons and neutrinos), charged particles are usually called cosmic rays.

When discussing cosmic rays, it is necessary to clarify which rays are being discussed. The following types of cosmic rays are distinguished:

1. Galactic cosmic rays - cosmic particles coming to the Earth from the bowels of our Galaxy. They do not include particles generated by the sun.

2. Solar cosmic rays - cosmic particles generated by the sun.

The flux of galactic cosmic rays bombarding the Earth is approximately isotropic and constant in time and amounts to 1 particle / cm 2 sec (before entering the Earth's atmosphere). The energy density of galactic cosmic rays is 1 eV / cm 3, which is comparable to the total energy of electromagnetic radiation from stars, the thermal motion of interstellar gas and the galactic magnetic field. Thus, cosmic rays are an important component of the Galaxy.

Composition of galactic cosmic rays:

Nuclear component- 93% protons, 6.5% helium nuclei,<1% более тяжелых ядер (т.е. отвечает распространенности ядер во Вселенной).

Electrons. Their number is 1% of the number of cores.

Positrons. Their number is 10% of the number of electrons.

Anti-Hadrons make up less than 1%.

The energies of galactic cosmic rays cover a huge range - not less than 15 orders of magnitude (10 6 -10 21 eV). Their flux for particles with E> 10 9 eV rapidly decreases with increasing energy. The energy spectrum of the nuclear component, excluding low energies, obeys the expression

n (E) = n o E -, (15.5)

where n o is a constant, and 2.7 for E<10 15 ýÂ è 3.1-3.2 ïðè E>10 15 eV. The energy spectrum of the nuclear component is shown in Figure 15.6.

The flux of ultrahigh-energy particles is extremely small. So, on average, no more than one particle with an energy of 10 20 eV falls on an area of ​​10 km 2 per year. The nature of the spectrum for electrons with energies> 10 9 eV is similar to that shown in Fig. 15.6. The flux of galactic cosmic rays has not changed for at least 1 billion years.

Galactic cosmic rays are obviously of non-thermal origin. Indeed, the maximum temperatures (10 9 K) are reached in the center of the stars. In this case, the energy of the thermal motion of the particles is 10 5 eV. At the same time, the particles of galactic cosmic rays reaching the vicinity of the Earth, generally have energies> 10 8 Â.

Rice. 15.6. Energy spectrum of the nuclear component of space

rays. Energy is given in the center of mass system.

There are good reasons to believe that cosmic rays are generated mainly by supernova explosions (other sources of cosmic rays are pulsars, radio galaxies, quasars). In our Galaxy, supernova explosions occur on average at least once every 100 years. It is easy to calculate that to maintain the observed energy density of cosmic rays (1 eV / cm 3), it is enough for them to transfer only a few percent of the explosion power. Protons, heavier nuclei, electrons and positrons ejected during supernova explosions are further accelerated in specific astrophysical processes (they will be discussed below), acquiring the energy characteristics inherent in cosmic rays.

In the composition of cosmic rays, there are practically no metagalactic rays, i.e. trapped in our Galaxy from the outside. All the observed properties of cosmic rays can be explained on the basis of the fact that they are formed, accumulated and held for a long time in our Galaxy, slowly flowing out into intergalactic space. If cosmic particles were moving in a straight line, they would go out of the Galaxy several thousand years after their appearance. Such a rapid leak would lead to irreplaceable losses and a sharp decrease in the intensity of cosmic rays.

In fact, the presence of an interstellar magnetic field with a highly entangled configuration of field lines makes charged particles move along complex trajectories (this movement resembles the diffusion of molecules), increasing the residence time of these particles in the Galaxy by a factor of thousands. The age of the bulk of cosmic ray particles is estimated at tens of millions of years. Cosmic particles of ultra-high energies are weakly deflected by the galactic magnetic field and leave the Galaxy relatively quickly. This may explain the break in the spectrum of cosmic rays at an energy of 310 15 A.

Let us dwell very briefly on the problem of the acceleration of cosmic rays. Particles of cosmic rays move in a discharged and electrically neutral cosmic plasma. It does not have significant electrostatic fields capable of accelerating charged particles due to the potential difference between different points of the trajectory. But in plasma electric fields of induction and pulsed type can arise. So an induction (vortex) electric field appears, as is known, with an increase in the magnetic field strength with time (the so-called betatron effect). The acceleration of particles can also be caused by their interaction with the electric field of plasma waves in regions with intense plasma turbulence. There are other acceleration mechanisms that we cannot dwell on in this course. A more detailed examination shows that the proposed acceleration mechanisms are capable of providing an increase in the energy of charged particles ejected in supernova explosions from 10 5 to 10 21 BV.

The charged particles emitted by the Sun - the solar cosmic rays - are a very important component of the cosmic radiation that bombards the Earth. These particles are accelerated to high energies in the upper part of the Sun's atmosphere during solar flares. Solar flares are subject to specific time cycles. The most powerful are repeated with a period of 11 years, the less powerful - with a period of 27 days. Powerful solar flares can increase the flux of cosmic rays falling on the Earth from the Sun by 10 6 times compared to the galactic one.

Compared to galactic cosmic rays, solar cosmic rays contain more protons (up to 98-99% of all nuclei) and, accordingly, fewer helium nuclei (1.5%). There are practically no other cores in them. The content of Z2 nuclei in solar cosmic rays reflects the composition of the solar atmosphere. The energies of particles of solar cosmic rays vary in the range of 10 5 -10 11 eV. Their energy spectrum has the form of a power-law function (15.5), where - decreases from 7 to 2 as the energy decreases.

All the above characteristics of cosmic rays refer to cosmic particles before entering the Earth's atmosphere, i.e. to the so-called primary cosmic radiation... As a result of interaction with the nuclei of the atmosphere (mainly oxygen and nitrogen), high-energy particles of primary cosmic rays (primarily protons) create a large number of secondary particles - hadrons (pions, protons, neutrons, antinucleons, etc.), leptons (muons, electrons, positrons, neutrinos) and photons. A complex multistage cascade process is developing. The kinetic energy of secondary particles is spent mainly on the ionization of the atmosphere.

The thickness of the earth's atmosphere is about 1000 g / cm 2. At the same time, the ranges of high-energy protons in air are 70-80 g / cm 2, and helium nuclei are 20-30 g / cm 2. Thus, a high-energy proton can experience up to 15 collisions with atmospheric nuclei, and the probability of reaching sea level near the primary proton is extremely small. The first collision usually occurs at an altitude of 20 km.

Leptons and photons appear as a result of weak and electromagnetic decays of secondary hadrons (mainly pions) and the production of e - e + pairs by quanta in the Coulomb field of nuclei:

ÿî + î + e - + e +.

Thus, instead of one primary particle, a large number of secondary ones appear, which are divided into hadronic, muonic and electron-photon components. An avalanche-like increase in the number of particles can lead to the fact that at the maximum of the cascade their number can reach 10 6 -10 9 (at the energy of the primary proton> 10 14 eV). Such a cascade covers a large area (many square kilometers) and is called extensive air shower(Figure 15.7).

After reaching the maximum size, the cascade decays mainly due to the loss of energy for ionization of the atmosphere. Mainly relativistic muons reach the Earth's surface. The electron-photon component is absorbed more strongly and the hadronic component of the cascade “dies out” almost completely. In general, the flux of cosmic ray particles at sea level is about 100 times less than the flux of primary cosmic rays, amounting to about 0.01 particles / cm 2 s.

Cosmic rays
Cosmic rays

Cosmic rays (cosmic radiation) - particles that fill interstellar space and constantly bombard the Earth. They were discovered in 1912 by the Austrian physicist W. Hess using an ionization chamber in a balloon. The maximum energies of cosmic rays are ~ 3. 10 20 eV, i.e. are several orders of magnitude higher than the energies available to modern accelerators on colliding beams (the maximum equivalent energy of the Tevatron is ~ 2.1015 eV, LHC is about 1017 eV). Therefore, the study of cosmic rays plays an important role not only in the physics of space, but also in the physics of elementary particles. A number of elementary particles were for the first time
discovered precisely in cosmic rays (positron - K.D. Anderson, 1932; muon (μ) - K.D. Anderson and S. Neddermeier, 1937; pion (π) - S.F. Powell, 1947 .). Although cosmic rays include not only charged, but also neutral particles (especially a lot of photons and neutrinos), charged particles are usually called cosmic rays.
There are the following types of cosmic rays (Fig. 1):

1. Galactic cosmic rays- cosmic particles coming to Earth from our galaxy. They do not include particles generated by the sun.
2. Solar cosmic rays- cosmic particles generated by the sun.

In addition to these two main types of cosmic rays, they also consider metagalactic cosmic rays - cosmic particles that originated outside our galaxy. Their contribution to the total flux of cosmic rays is small.
Cosmic rays that are not distorted by interaction with the Earth's atmosphere are called primary... The flux of galactic cosmic rays bombarding the Earth is approximately isotropic and constant in time and amounts to ~ 1 particle / cm 2. s (before entering the Earth's atmosphere). The energy density of galactic cosmic rays is ~ 1 eV / cm 3, which is comparable to the total energy of the electromagnetic radiation of stars, the thermal motion of interstellar gas and the galactic magnetic field. Thus, cosmic rays are an important component of the Galaxy.
The composition of cosmic rays is given in the table.

Figure 2 on the left shows the energy spectra of the main components of primary cosmic rays. Figure 2 on the right shows the vertical fluxes of the main components of cosmic rays with energies> 1 GeV in the Earth's atmosphere. In addition to protons and electrons, all particles arose as a result of the interaction of primary cosmic rays with the nuclei of the atmosphere.

As a result of interaction with the nuclei of the atmosphere, primary cosmic rays (mainly protons) create a large number of secondary particles - pions, protons, neutrons, muons, electrons, positrons and photons. Thus, instead of one primary particle, a large number of secondary particles appear, which are divided into hadronic, muonic and electron-photon components. Such a cascade covers a large area and is called extensive air shower .
In one act of interaction, a proton usually loses ~ 50% of its energy, and as a result of the interaction, mainly pions appear. Each subsequent interaction of the primary particle adds new hadrons to the cascade, which fly mainly in the direction of the primary particle, forming a hadron root.
The resulting pions can interact with the nuclei of the atmosphere, or they can decay, forming the muonic and electron-photon components of the shower. The hadronic component practically does not reach the Earth's surface, turning into muons, neutrinos and γ-quanta as a result of decays.

π 0 → 2γ,
π + (or K +) → μ + + ν μ,
π - (or K -) → μ - + μ,
K +, -, 0 → 2π,
μ + → e + + ν e + μ,
μ - → e - + e + ν μ.

Formed during the decay of neutral pions, -quants give rise to electron-positron pairs and -quants of subsequent generations. Charged leptons lose energy for ionization and radiative deceleration. Relativistic muons mainly reach the Earth's surface. The electron-photon component is absorbed more strongly.
One proton with energy> 10 14 eV can create 10 6 -10 9 secondary particles. On the Earth's surface, shower hadrons are concentrated in a region of the order of several meters, the electron-photon component is in the region of ~ 100 m, and the muon component is several hundred meters.
The cosmic ray flux at sea level (~ 0.01 cm -2 · s -1) is about 100 times less than the primary cosmic ray flux.
The main sources of primary cosmic rays are supernova explosions (galactic cosmic rays) and the Sun. Big energies
(up to 10 16 eV) of galactic cosmic rays are explained by the acceleration of particles on shock waves formed during supernova explosions. The nature of ultrahigh-energy cosmic rays has not yet been unambiguously interpreted.

Almost a hundred years have passed since the moment when cosmic rays were discovered - streams of charged particles coming from the depths of the Universe. Since then, many discoveries have been made related to cosmic radiation, but many mysteries still remain. One of them, perhaps the most intriguing: where do particles with an energy of more than 1020 eV, that is, almost a billion trillion electron volts, a million times greater than will be obtained in the most powerful accelerator - the Large Hadron Collider LHC? What forces and fields accelerate particles to such monstrous energies?

Cosmic rays were discovered in 1912 by the Austrian physicist Victor Hess. He was a member of the Vienna Radium Institute and carried out research on ionized gases. By that time, they already knew that all gases (including the atmosphere) were always slightly ionized, which indicated the presence of a radioactive substance (like radium) either in the composition of the gas or near an instrument measuring ionization, most likely in the earth's crust. Experiments with raising the ionization detector in a balloon were conceived to test this assumption, since the ionization of the gas should decrease with distance from the earth's surface. The answer was the opposite: Hess discovered a certain radiation, the intensity of which increased with height. This suggested that it comes from space, but it was possible to finally prove the extraterrestrial origin of the rays only after numerous experiments (V. Hess was awarded the Nobel Prize only in 1936). Recall that the term "radiation" does not mean that these rays are purely electromagnetic in nature (like sunlight, radio waves, or X-rays); it was used to discover a phenomenon whose nature was not yet known. And although it soon became clear that the main component of cosmic rays is accelerated charged particles, protons, the term has survived. The study of a new phenomenon quickly began to yield results that are commonly referred to as the "cutting edge of science."

The discovery of cosmic particles of very high energy immediately (long before the proton accelerator was created) raised the question: what is the mechanism of acceleration of charged particles in astrophysical objects? Today we know that the answer turned out to be non-trivial: a natural, "space" accelerator is fundamentally different from man-made accelerators.

It soon became clear that cosmic protons, flying through matter, interact with the nuclei of its atoms, giving rise to previously unknown unstable elementary particles (they were observed primarily in the Earth's atmosphere). The study of the mechanism of their birth opened a fruitful way for the construction of a systematics of elementary particles. in the laboratory, protons and electrons have learned to accelerate and receive their huge fluxes, incomparably denser than in cosmic rays. Ultimately, it was the experiments on the interaction of particles that received energy in accelerators that led to the creation of a modern picture of the microworld.

In 1938, the French physicist Pierre Auger discovered a remarkable phenomenon - showers of secondary cosmic particles, which arise as a result of the interaction of primary protons and extremely high-energy nuclei with the nuclei of atoms in the atmosphere. It turned out that the spectrum of cosmic rays contains particles with energies of the order of 1015-1018 eV - millions of times more energy than particles accelerated in the laboratory. Academician Dmitry Vladimirovich Skobeltsyn attached particular importance to the study of such particles and immediately after the war, in 1947, together with his closest colleagues G.T.Zatsepin and N.A. ... The history of the first studies of cosmic rays can be found in the books by N. Dobrotin and V. Rossi. Over time, the school of D.V.Skobeltsyn grew into one of the strongest in the world and for many years determined the main directions in the study of ultrahigh-energy cosmic rays. Her methods made it possible to expand the range of investigated energies from 109-1013 eV, recorded on balloons and satellites, to 1013-1020 eV. Two aspects made these studies particularly attractive.

First, it became possible to use high-energy protons created by nature itself to study their interaction with the nuclei of atoms in the atmosphere and decipher the finest structure of elementary particles.

Secondly, there is a possibility of finding objects in space that can accelerate particles to extremely high energies.

The first aspect turned out to be not as fruitful as desired: the study of the fine structure of elementary particles required much more data on the interaction of protons than can be obtained by cosmic rays. At the same time, an important contribution to the concept of the microworld was made by the study of the dependence of the most general characteristics of the interaction of protons on their energy. It was during the study of EAS that a feature was discovered in the dependence of the number of secondary particles and their energy distribution on the energy of the primary particle, associated with the quark-gluon structure of elementary particles. These data were later confirmed in accelerator experiments.
Today, reliable models of the interaction of cosmic rays with the nuclei of atoms of the atmosphere have been built, which made it possible to study the energy spectrum and the composition of their primary particles of the highest energies. It became clear that cosmic rays play no less a role in the dynamics of the development of the Galaxy than its fields and flows of interstellar gas: the specific energy of cosmic rays, gas and magnetic field is approximately equal to 1 eV per cm3. With such a balance of energy in the interstellar medium, it is natural to assume that the acceleration of cosmic ray particles occurs, most likely, in the same objects that are responsible for heating and ejection of gas, for example, in New and Supernova stars when they explode.

The first mechanism for the acceleration of cosmic rays was proposed by Enrico Fermi for protons that randomly collide with magnetized clouds of interstellar plasma, but he could not explain all the experimental data. In 1977, Academician Germogen Filippovich Krymsky showed that this mechanism should accelerate much more strongly the particles in the remnants of Supernovae at the fronts of shock waves, the velocities of which are orders of magnitude higher than the velocities of clouds. Today it has been reliably shown that the mechanism of acceleration of cosmic protons and nuclei by a shock wave in supernova envelopes is the most effective. But it will hardly be possible to reproduce it in laboratory conditions: the acceleration is relatively slow and requires huge expenditures of energy to hold the accelerated particles. In supernova envelopes, these conditions exist due to the very nature of the explosion. It is remarkable that the acceleration of cosmic rays occurs in a unique astrophysical object, which is responsible for the synthesis of heavy nuclei (heavier than helium), which are actually present in cosmic rays.

In our Galaxy, there are several known supernovae less than a thousand years old that have been observed with the naked eye. The most famous are the Crab Nebula in the constellation Taurus ("Crab" is the remnant of the Supernova outburst in 1054, noted in the eastern annals), Cassiopeia A (observed in 1572 by the astronomer Tycho Brahe) and Kepler's Supernova in the constellation Ophiuchus (1680). The diameters of their shells today are 5-10 light years (1 light year = 1016 m), that is, they expand at a speed of the order of 0.01 the speed of light and are at a distance of about ten thousand light years from Earth. Supernova envelopes ("nebulae") in the optical, radio, X-ray and gamma ranges were observed by the space observatories Chandra, Hubble and Spitzer. They have shown reliably that acceleration of electrons and protons, accompanied by X-ray radiation, actually occurs in the shells.

Fill interstellar space with cosmic rays with a measured specific energy (~ 1 eV per cm3) could be about 60 supernova remnants younger than 2000 years old, while less than ten of them are known. This shortage is explained by the fact that in the plane of the Galaxy, where the stars and supernovae are concentrated, there is a lot of dust, which does not let light through to the observer on Earth. Observations in X-rays and gamma rays, for which the dust layer is transparent, made it possible to expand the list of observed "young" Supernova shells. The latest of these newly discovered shells is the Supernova G1.9 + 0.3, observed with the Chandra X-ray telescope since January 2008. Estimates of the size and expansion rate of its shell show that it flared up about 140 years ago, but was not visible in the optical range due to the complete absorption of its light by the dusty layer of the Galaxy.

In addition to the data on Supernovae exploding in our Milky Way Galaxy, there are significantly richer statistics on Supernovae in other galaxies. A direct confirmation of the presence of accelerated protons and nuclei is gamma radiation with high energy of photons arising from the decay of neutral pions - the products of the interaction of protons (and nuclei) with the source matter. Such photons of the highest energies are observed with telescopes that register the Vavilov - Cherenkov glow emitted by secondary particles of EAS. The most advanced instrument of this type is a six-telescope setup created in collaboration with HESS in Namibia. The gamma radiation from the Crab was measured first, and its intensity became a measure of intensity for other sources.

The result obtained not only confirms the existence of a mechanism for the acceleration of protons and nuclei in a Supernova, but also allows one to estimate the spectrum of accelerated particles: the spectra of "secondary" gamma quanta and "primary" protons and nuclei are very close. The magnetic field in the Crab and its size allows the acceleration of protons to energies of the order of 1015 eV. The spectra of cosmic ray particles in the source and in the interstellar medium are somewhat different, since the probability of particle escape from the source and the lifetime of particles in the Galaxy depend on the energy and charge of the particle. Comparison of the energy spectrum and composition of cosmic rays, measured near the Earth, with the spectrum and composition in the source, made it possible to understand how long particles travel among stars. The nuclei of lithium, beryllium and boron in cosmic rays near the Earth turned out to be much larger than in the source - their additional amount appears as a result of the interaction of heavier nuclei with interstellar gas. Having measured this difference, we calculated the amount X of the substance through which the cosmic rays passed, wandering in the interstellar medium. In nuclear physics, the amount of matter that a particle meets on its way is measured in g / cm2. This is due to the fact that in order to calculate the decrease in the particle flux in collisions with nuclei of matter, it is necessary to know the number of collisions of a particle with nuclei having a different area (cross section) transverse to the direction of the particle. Expressing the amount of matter in these units, a single measurement scale is obtained for all nuclei.

The experimentally found value of X ~ 5-10 g / cm2 makes it possible to estimate the lifetime t of cosmic rays in the interstellar medium: t ≈ X / ρc, where c is the particle velocity, approximately equal to the speed of light, ρ ~ 10-24 g / cm3 is the average density of the interstellar medium. Hence, the lifetime of cosmic rays is about 108 years. This time is much longer than the time of flight of a particle moving with speed c in a straight line from the source to the Earth (3 × 104 years for the most distant sources on the opposite side of the Galaxy from us). This means that the particles do not move in a straight line, but undergo scattering. Chaotic magnetic fields of galaxies with induction B ~ 10-6 gauss (10-10 Tesla) move them in a circle with a radius (gyroradius) R = E / 3 x 104B, where R in m, E is the particle energy in eV, B is the magnetic induction fields in gauss. At moderate energies of particles E< 1017 эВ, полученных в ускорителях-Сверхновых, гирорадиус оказывается значительно меньше размера Галактики (3·1020 м).

Only particles with energies E> 1019 eV will come approximately in a straight line from the source. Therefore, the direction of the EAS particles with energies less than 1019 eV does not indicate their source. In this energy range, it remains only to observe the secondary radiation generated in the sources themselves by protons and nuclei of cosmic rays. In the observable energy range of gamma radiation (E< 1013 эВ) данные о направлении прихода его квантов убедительно показывают, что космические лучи излучают объекты, сконцентрированные в плоскости нашей Галактики. Там же сосредоточено и межзвёздное вещество, с которым взаимодействуют частицы космических лучей, генерируя вторичное гамма-излучение.

The concept of cosmic rays as a "local" galactic phenomenon turned out to be true only for particles of moderate energies E< 1017 эВ. Ограниченные возможности Галактики как ускорять, так и удерживать частицы с особенно высокой энергией были убедительно продемонстрированы в опытах по измерению энергетического спектра космических лучей.

In 1958, Georgy Borisovich Christiansen and German Viktorovich Kulikov discovered a sharp change in the form of the energy spectrum of cosmic rays at an energy of the order of 3 × 1015 eV. At energies below this value, the experimental data on the particle spectrum were usually presented in a "power-law" form so that the number of particles N with a given energy E was considered inversely proportional to the particle energy in the power γ: N (E) = a / Eγ (γ is the differential spectrum exponent ). Up to an energy of 3 · 1015 eV, the exponent γ = 2.7, but upon going over to high energies, the energy spectrum experiences a "break": for energies E> 3 · 1015 eV, γ becomes 3.15. It is natural to associate this change in the spectrum with the approach of the energy of accelerated particles to the maximum possible value calculated for the acceleration mechanism in supernovae. The nuclear composition of primary particles in the energy range of 1015-1017 eV also speaks in favor of such an explanation for the break in the spectrum. The most reliable information about it is provided by complex EAS installations - "MGU", "Tunka", "Tibet", "Kaskad". With their help, not only information about the energy of primary nuclei is obtained, but also parameters depending on their atomic numbers - the "width" of the shower, the ratio between the number of electrons and muons, between the number of the most energetic electrons and their total number. All these data indicate that with an increase in the energy of primary particles from the left edge of the spectrum before its break to the energy after the break, their average mass increases. Such a change in the composition of particles by mass is consistent with the model of particle acceleration in Supernovae - it is limited by the maximum energy, which depends on the particle charge. For protons, this maximum energy is of the order of 3 × 1015 eV and increases in proportion to the charge of the accelerated particle (nucleus), so that iron nuclei are effectively accelerated up to ~ 1017 eV. The intensity of particle fluxes with energies exceeding the maximum decreases rapidly.

But the registration of particles of even higher energies (~ 3 · 1018 eV) showed that the spectrum of cosmic rays not only does not break off, but returns to the form observed before the break!

Measurements of the energy spectrum in the "ultrahigh" energy region (E> 1018 eV) are very difficult because of the small number of such particles. To observe these rare events, it is necessary to create a network of EAS particle flux detectors and Vavilov - Cherenkov radiation generated by them in the atmosphere and ionization radiation (atmospheric fluorescence) over an area of ​​hundreds and even thousands of square kilometers. For such large, complex installations, they choose places with limited economic activity, but with the ability to ensure the reliable operation of a huge number of detectors. Such installations were first built on areas of tens of square kilometers (Yakutsk, Havera Park, Akeno), then in hundreds (AGASA, Fly's Eyе, HiRes), and, finally, installations in thousands of square kilometers are now being created (Pierre Auger observatory in Argentina, Telescopic installation in Utah, USA).

The next step in the study of ultrahigh energy cosmic rays will be the development of a method for recording EASs by observing atmospheric fluorescence from space. In cooperation with several countries, the first EAS space detector, the TUS project, is being created in Russia. Another such detector is supposed to be installed on the International Space Station ISS (projects JEM-EUSO and KLPVE).

What do we know about ultra-high energy cosmic rays today? The lower figure shows the energy spectrum of cosmic rays with energies above 1018 eV, which was obtained at the latest generation devices (HiRes, Pierre Auger Observatory), together with data on cosmic rays of lower energies, which, as was shown above, belong to the Milky Way Galaxy. It can be seen that at energies of 3 · 1018-3 · 1019 eV, the index of the differential energy spectrum decreased to a value of 2.7-2.8, exactly the same that is observed for galactic cosmic rays, when the particle energies are much less than the maximum possible for galactic accelerators. Does this not serve as an indication that at ultrahigh energies the main stream of particles is created by accelerators of extragalactic origin with maximum energies much higher than galactic ones? A kink in the spectrum of galactic cosmic rays shows that the contribution of extragalactic cosmic rays changes sharply upon going from the region of moderate energies 1014-1016 eV, where it is about 30 times less than the contribution of galactic ones (the spectrum indicated by the dashed line in the figure), to the region of ultrahigh energies, where he becomes dominant.

In recent decades, numerous astronomical data have been accumulated on extragalactic objects capable of accelerating charged particles to energies much higher than 1019 eV. An obvious sign that an object of size D can accelerate particles to energy E is the presence of a magnetic field B throughout this object such that the gyroradius of the particle is less than D. These candidate sources include radio galaxies (emitting strong radio emissions); nuclei of active galaxies containing black holes; colliding galaxies. All of them contain jets of gas (plasma) moving at tremendous speeds approaching the speed of light. Such jets play the role of shock waves necessary for the operation of the accelerator. To estimate their contribution to the observed intensity of cosmic rays, it is necessary to take into account the distribution of sources over distances from the Earth and the energy loss of particles in intergalactic space. Before the discovery of the background cosmic radio emission, intergalactic space seemed "empty" and transparent not only for electromagnetic radiation, but also for ultra-high energy particles. The density of gas in intergalactic space, according to astronomical data, is so small (10–29 g / cm3) that even at huge distances of hundreds of billions of light years (1024 m), particles do not meet the nuclei of gas atoms. However, when it turned out that the Universe is filled with low-energy photons (about 500 photons / cm3 with an energy of Ef ~ 10–3 eV) left after the Big Bang, it became clear that protons and nuclei with an energy of more than E ~ 5 · 1019 eV, the limit Greisen - Zatsepin - Kuzmin (GZK), must interact with photons and lose most of their energy on the way over tens of millions of light years. Thus, the overwhelming part of the Universe, located at distances of more than 107 light years from us, turned out to be inaccessible for observation in rays with an energy of more than 5 · 1019 eV. Recent experimental data on the spectrum of ultra-high energy cosmic rays (HiRes facility, Pierre Auger Observatory) confirm the existence of this energy limit for particles observed from Earth.

As can be seen, it is extremely difficult to study the origin of ultra-high energy cosmic rays: the main part of possible sources of cosmic rays of the highest energies (above the GZK limit) are so far away that particles on their way to the Earth lose the energy acquired in the source. And at energies below the GZK limit, the deflection of particles by the magnetic field of the Galaxy is still large, and the direction of arrival of particles can hardly indicate the position of the source on the celestial sphere.

In the search for ultrahigh-energy cosmic ray sources, an analysis of the correlation of the experimentally measured direction of arrival of particles with sufficiently high energies is used - such that the fields of the Galaxy slightly deflect particles from the direction to the source. Installations of the previous generation have not yet provided convincing data on the correlation of the direction of arrival of particles with the coordinates of any specially selected class of astrophysical objects. The latest data from the Pierre Auger Observatory can be regarded as a hope for obtaining data in the coming years on the role of AGN-type sources in the creation of intense fluxes of particles with energies of the order of the GZK limit.

It is interesting that the AGASA facility provided indications of the existence of "empty" directions (those where there are no known sources) along which two or even three particles arrive during the observation period. This aroused great interest among physicists involved in cosmology - the science of the origin and development of the Universe, inextricably linked with the physics of elementary particles. It turns out that in some models of the structure of the microworld and the development of the Universe (the Big Bang theory), the preservation in the modern Universe of supermassive elementary particles with a mass of about 1023-1024 eV is predicted, of which matter should consist at the earliest stage of the Big Bang. Their distribution in the Universe is not very clear: they can either be uniformly distributed in space, or "attracted" to massive regions of the Universe. Their main feature is that these particles are unstable and can decay into lighter ones, including stable protons, photons and neutrinos, which acquire huge kinetic energies - more than 1020 eV. Places where such particles have survived (topological defects of the Universe) may turn out to be sources of ultrahigh energy protons, photons or neutrinos.

As in the case of galactic sources, the existence of extragalactic ultrahigh-energy cosmic ray accelerators is confirmed by data from gamma-ray detectors, for example, telescopes of the HESS facility, aimed at the extragalactic objects listed above - candidates for cosmic ray sources.

Among them, the most promising are the nuclei of active galaxies (AGN) with jets of gas. One of the most well-studied objects at the HESS facility is the M87 galaxy in the constellation Virgo, at a distance of 50 million light years from our Galaxy. At its center is a black hole, which provides energy for the processes near it and, in particular, a giant jet of plasma belonging to this galaxy. The acceleration of cosmic rays in M87 is directly confirmed by observations of its gamma radiation, the energy spectrum of photons of which with an energy of 1-10 TeV (1012-1013 eV), observed at the HESS facility. The observed intensity of gamma radiation from M87 is approximately 3% of that of the Crab. Taking into account the difference in the distance to these objects (5000 times), this means that the luminosity of M87 exceeds the luminosity of the Crab by 25 million times!

Particle acceleration models created for this object show that the intensity of particles accelerated in M87 can be so great that even at a distance of 50 million light years, the contribution of this source can provide the observed intensity of cosmic rays with energies above 1019 eV.

But here's a mystery: in modern data on EASs towards this source, there is no excess of particles with energies of the order of 1019 eV. Will this source not manifest itself in the results of future space experiments, at such energies, when distant sources no longer contribute to the observed events? The situation with a break in the energy spectrum can be repeated once more, for example, at an energy of 2 · 1020. But this time the source should be visible in the measurements of the direction of the trajectory of the primary particle, since the energies> 2 · 1020 eV are so great that the particles should not be deflected in galactic magnetic fields.

As you can see, after a hundred-year history of studying cosmic rays, we are again waiting for new discoveries, this time of ultra-high energy cosmic radiation, the nature of which is still unknown, but can play an important role in the structure of the Universe.

Literature

Dobrotin N.A. Cosmic rays. - M .: Ed. Academy of Sciences of the USSR, 1963.

Murzin V.S. Introduction to the physics of cosmic rays. - M .: Ed. Moscow State University, 1988.

Panasyuk MI Wanderers of the Universe, or the Echo of the Big Bang. - Fryazino: "Vek2", 2005.

Rossi B. Cosmic rays. - M .: Atomizdat, 1966.

Khrenov BA Relativistic meteors // Science in Russia, 2001, No. 4.

B. A. Khrenov and M. I. Panasyuk Messengers of the Cosmos: Far or Near? // Nature, 2006, no. 2.

1. Cosmic rays (CR) are a stream of charged high-energy particles arriving at the Earth's surface approximately isotropically from all directions of outer space. Distinguish between primary and secondary Cosmic rays.

Primary CL come to Earth from scythe They include galactic CRs, coming from galactic space, and solar CRs, born on the Sun during flares.

Secondary CL are born in the earth's atmosphere. They are formed during the interaction of primary CRs with atoms of atmospheric matter.

The discovery of CL will be associated with the study of the electrical conductivity of air. At the beginning of the XX century. It was reliably established that V0 "B0W, contained even in a sealed vessel, is always ionized. After the discovery of natural radioactivity, it became clear that the ionization source is located outside the vessel containing air, and is radioactive radiation from rocks. ...

In 1912, the Austrian Victor Hess took off in a balloon with an electroscope in a hermetically sealed vessel, the air pressure in which remained constant. He found that during the ascent to the first 600 m, the ionization of the air decreased. But, starting from 600 m, it began to increase the higher the faster. At an altitude of 4800 m, the concentration of ions became 4 times higher than at sea level. Therefore, Hess suggested that ionizing radiation of a very high penetrating ability falls on the boundary of the earth's atmosphere from world space.

Later experiments were carried out with balloon-probes. It turned out that at an altitude of 8400 m, ionization is 10 times greater than at sea level. At an altitude of 20 km, it reaches a maximum, and with further rise it begins to decrease. This is explained by the fact that at an altitude of 20 km as a result of interaction (the atmosphere of primary CRs creates the highest concentration of secondary ionizing particles.

2. Primary cosmic rays (PCR)... Consider the energy spectrum, composition, range, and acceleration mechanism of particles in PCR

a... The PCR energy is very high. For most particles, it exceeds 10 GeV. Therefore, the main preset in the detection of PCR particles is that the particles are decelerated within the detector. Only in this case can their total energy be measured.

For the first time, the PCR energy spectrum was directly measured on the Proton satellites in 1965-69. Later, these measurements were repeated on the satellites of the Moon and Mars outside the Earth's magnetic field. The energy of PCR particles was measured using an ionization calorimeter. The device is a system of layers of nuclear targets, photographic plates and counters. Interacting with the target nuclei (heavy metal), the cosmic particle generates a flux of hard γ-quanta. In the layers of lead, these γ-quanta generate powerful avalanches of ionizing particles, which are recorded in photographic emulsions and counters. If the thickness of the calorimeter layers is large and all the particles of the avalanche remain in it, then by their number it is possible to determine the energy of the primary cosmic particle. Ionization calorimeters have a volume of up to several cubic meters. meters and weight up to 20 tons.

Figure 166 shows the dependence of the intensity I of the flux of PCR particles on their energy E on a logarithmic scale. Intensity I is expressed by the number of particles per 1 m 2 of the earth's surface from a solid angle of 1 sr in 1 s. Energy E is indicated in GeV (1 GeV = 109V).

In the range of energies E from 10 to 10 6 GeV, the energy spectrum is described by the empirical formula I = AE - γ, food A = 10 18 h / m2 sr-s, γ = 1.6.

The total PCR flux is approximately 104 private / m2 sr. The maximum PCR energy reaches 10 11 GeV. This means that the PCR is a unique source of ultrahigh energies, since the maximum energy obtained at accelerators does not exceed 10 5 GeV. But there are very few particles with energies E> 10 6 GeV. On the average, one such particle per year falls on an area of ​​1 m 2.

The PCR energy is of non-thermal origin. So, inside the stars, the average energy of particles is Eav = 3kT / 2 = 3 * 1.4 * 10 -23 * 10 9/2 = 2.1 * 10 -14 J = 0.1 MeV. And the average energy of PCR particles near the Earth is 100 MeV, that is, 1000 times more. This means that cosmic particles are accelerated in some astrophysical processes of an electromagnetic nature.

b... PCL composition. Primary cosmic radiation at the location of the solar system is isotropic in direction and constant in time. According to its composition, the PCL is subdivided into the following groups.

p-group. Contains hydrogen nuclei - protons 1 1 r, deuterons 2 1 D, tritons 3 1 T

α-group. Contains helium nuclei 4 2 He, 3 2 He.

L - group (from English light - light). Contains light nuclei of lithium, beryllium and boron.

M-group (mesolight - medium light). Contains nuclei from carbon C to fluorine F.

H - group (heavy - heavy). Contains heavy nuclei from neon Ne to potassium K.

VH - band (very heavy - very heavy). Contains nuclei from calcium Ca (Z = 20) to zinc Zn (z = 30).

SH band (superheavy). Contains - nuclei starting with gallium Ca

E - group. Contains electrons e and positrons e +.

In contrast to the content of elements on average in the Universe, an increased content of medium and heavy nuclei is observed in the PCR: the group of medium nuclei L - 150,000 times, group H - 2.5 times, group VH - 60 times, group SH-n 14 times ...

The abundance of nuclei in the L group is especially prominent. It can be assumed that the nuclei of the L group arise in PCR as a result of collisions of nuclei with z> 6 with particles of interstellar gas, consisting mainly of hydrogen and helium. As a result of the fragmentation reaction, heavy nuclei are fragmented and nuclei of the L group are obtained. If we accept this hypothesis, then it is possible to estimate the average path traversed by a cosmic particle from its place of birth to the Earth.

v... Average range of particles in PCR. Let the cosmic gas from hydrogen nuclei fill space evenly. A parallel beam of particles propagates from a source generating heavy particles with a mass greater than the mass of the group nuclei along the OA1 axis. When heavy particles collide with hydrogen nuclei, light nuclei of group I are formed, moving in the same direction.

As a result of the crushing of heavy particles, the intensity I t of the beam of heavy particles

should decrease with distance according to Bouguer's law, I т = I т0 exp (-σNx), (25.2) where I then is the initial intensity of the beam of heavy particles, N is the concentration of hydrogen nuclei in the cosmic gas. σ is the effective cross section of the nuclear fragmentation reaction with the formation of nuclei of the L group. Let in each collision, when a heavy particle disappears, only one light particle of the L group appears. The intensity of the particle flux I will increase with distance according to the law I e, = I 0 - I т = I T . (25.3) The ratio of the intensity of light and heavy particles in PCR should increase with distance I l / I t = / exp (-σNx) = exp (-σNx) -1

Denoting the ratio I l / I t = n, we get: x = ln (n + l) / σN. (25.5). The ratio n = I l / I t = 15 / (52 + 15 + 4) = 1/5 = 0.2. From astrophysical estimates, the concentration of dust particles - hydrogen nuclei in space is approximately equal to 1 particle in 1 cm 3, so that n = 10 6 m -3. The effective cross section of fragmentation reactions observed under terrestrial conditions allows one to take the values ​​σ = 10 -30 m 2. Hence x = ln (1,2) / 10 -30 * 10 6 = 2 * 10 23 m.

Space distances in astrophysics are usually expressed in parsecs. By definition, one parsec is the distance from which the diameter of the earth's orbit (150 million km) is visible at an angle of 1 second. A parsec is a very long distance, 1 ps = 3 * 10 16 m. Expressed in parsecs, the path of the PCR particles to the Earth is x = 7000 kpc.

Astrophysical studies have established that our galaxy has the form of a biconvex lens 25 kpc in diameter and up to 2 kpc thick, surrounded by a cosmic gas Halo in the form of a sphere. Comparison of the value of x obtained in the estimates with the size of the Galaxy shows that x = 7000 kpc many times

is larger not only the diameter of the Galaxy (25 kpc), but also the diameter of the Halo (30 kpc). Hence, it follows that PCRs are born outside our Galaxy.

Apparently, this conclusion is not correct. First, it was assumed that in each fragmentation reaction only one particle of the L group is born. In fact, more of them can be born. Therefore, an increase in the flux of particles of the L group can occur faster and at a smaller distance x. Second, it was assumed that in all collisions the direction of motion of the particles does not change. But this is not the case. The nature of the motion of PCR particles is closer to the motion of Brownian particles. Their trajectory is a broken line. Therefore, PCR particles can travel much longer paths inside the Galaxy in comparison with its size.

More rigorous estimates lead to the conclusion that at least 90% of PCR particles (galactic rays) are born inside the Galaxy. And only about 10% of PCR particles come from outside the Galaxy (metagalactic rays). Due to the diffuse nature of the motion of cosmic particles, information about the position of sources of charged particles is erased. Therefore, cosmic radiation, with the exception of EM-field quanta, is isotropic.

G. PCR particle acceleration mechanism... Fermi's hypothesis is most likely. He suggested that supernova explosions form extended magnetized plasma clouds, scattering from the epicenter of the explosion at tremendous speeds. Charged particles in head-on collisions with such clouds are reflected from them. In accordance with the law of conservation of momentum, the absolute radial component of the particle velocity increases by twice the speed of the cloud, υ 2 R = - υ 1 R + 2υ 0. If the particle catches up with the cloud, then its speed decreases. But such particles can only be those that were born inside the star. And for those particles that are outside the star, counter movements are realized. Therefore, the kinetic energy of cosmic particles grows with time.

3. Origin of PKJI... Four main sources of PCR can be distinguished: new stars,

supernovae, pulsars, quasars.

a. New Stars (NZ) are close binary stellar systems with a total mass of 1-5 solar masses, orbiting around a common center of mass. Before the outburst, they have a visual magnitude of 4-5 units.

During an outbreak within 1-100 Earth days, their luminosity increases 100-1000000 times. After that, within several years, it weakens to its original value. During a flash, the NS emits about 10 38 J of energy. Several years after the outburst, a spherical gas envelope with a radial expansion velocity = 1000 km / s is found at the site of the NS. The mass of the shell is about 0.01 solar masses, its kinetic energy is about 10 39 J.

The reason for the NS outburst is that accretion occurs in the binary system - the flow of matter from a cold red dwarf to a hot white dwarf. As a result, in a hot star, the balance between gravitational forces, on the one hand, and the forces of optical and gas-kinetic pressure, on the other, is disturbed. This leads to the explosion of a hot star.

UZ flashes are common. 100-200 NS flares up in our Galaxy per year. They are not of a catastrophic nature and are repeated in some stars after months and years. Some fraction of PCR particles can originate from NS shells.

b. Supernovae (SNZ)... The so-called stars, the luminosity of which during an outbreak becomes commensurate with the luminosity of the galaxy to which it belongs. So, SNZ 1885, in the Andromeda nebula had the luminosity of the entire galaxy. The amount of energy emitted during an SNZ flash is of the order of 10 44 J. It is a million times greater than the energy of an NS flash. In our Galaxy, one SNZ flashes on average once every 300 years. The last SNZ was observed by Kepler in 1604 (Kepler's SNZ).

The maximum luminosity of the SNZ is 1-3 weeks. The shell ejected by the star has a mass of up to S solar masses and a speed of up to 20,000 km / s. Many PCR particles also originate from these shells. After the explosion of the SNZ, nebulae and pulsars are found in their place. To date, about 90 SNZ remains have been found. It can be assumed that the mechanism for the formation of SNZ is based on a regularity: the greater the mass of atomic nuclei, the higher the temperature the reaction of their thermonuclear fusion takes place.

When a protostar emerges from a gas and dust nebula, the entire space of the nebula is filled with hydrogen. Due to the gravitational contraction of the cloud, the temperature gradually rises. When the temperature T = 10 7 K is reached, a sluggish reaction of the synthesis of protons into deuterons begins. The proton-proton cycle starts.

The protostar heats up to glow and turns into a star. The gravitational forces are balanced by the forces of light gas kinetic pressure. The compression is paused. For the period of hydrogen burning, relative equilibrium is established.

After the bulk of the hydrogen turns into helium, the star begins to cool down, and the light pressure decreases rapidly. The helium fusion reaction does not start, since the temperature T 1 is not sufficient for the fusion of helium nuclei. In the process of gravitational contraction of the star, its temperature gradually increases. The forces of gravity are increasing directly

proportional to l / r 2, therefore, when the temperature T 1 is reached, equilibrium does not occur, since the temperature T 1 corresponds in this case to a smaller volume of the star. The compression and increase in temperature continue, and at a certain temperature T 2 = 10 8 K, the reaction of fusion of helium nuclei starts: 3 4 2 He-> 12 6 C + 7.22 MeV (τ = 10 years), and then: (25.6)

4 2 He + 12 8 C-> 16 8 O + γ, 4 2 He + 16 8 O-> 20 10 Ne + γ, 4 2 He + 20 10 Ne -> 24 12 Mg. (25.7)

After the helium burns out, a dense core of the star is formed, the core content of carbon C-12, oxygen 0-16, neon Ne-20, Magnesium Mg-24. Further, the course of the evolution of a star can proceed in the same way. At a certain temperature T 3> T 2, the reaction of synthesis of carbon-magnesium nuclei is excited. This cycle should end with the formation of silicon cores Si-26 and phosphorus P-31.

And, finally, at a temperature T 4> T 3, the last stage of the exothermic reaction of the synthesis of silicon and phosphorus nuclei can be excited, which should end with the formation of 56 26 Fe, 59 27 Co, 57 28 Ni nuclei.

This is an idealized scheme. In fact, these processes can overlap. In the center of a star, fusion reactions of heavier nuclei can take place at a higher temperature, and in the periphery, fusion reactions of less heavy nuclei at lower temperatures. And in most cases, the evolution of a star is calm. But sometimes there is such a combination of mass, composition, size and other parameters of a star that the equilibrium is disturbed. Under the influence of gravity, the substance of the star rapidly pushes towards the center, and the collapse of the star occurs. The high density, temperature and pressure in the core of a star can in some cases lead to the rapid release of huge energies. For example, as a result of this reaction: 16 8 O + 16 8 O = 32 16 S + 16.5 MeV. (25.8)

The star explodes, giving birth to a supernova. If we take into account the energy of the SNZ explosion E = 10 44 J and the frequency of their repetitions, it turns out that to maintain the average energy density of the PCR, 1% of the SNZ explosion is sufficient.

v. Pulsars(pulsating sources of radio emission) are small neutron stars, up to 20 km in diameter, formed as a result of the rapid gravitational compression of supernova remnants. The density of neutron stars reaches 1012 kg / m 3, which is close to the density of the matter of atomic nuclei.

As a result of the compression of the remnants of the star, the magnetic field induction on the surface reaches enormous values ​​of the order of 10 9 T. For comparison: the maximum magnetic field induction obtained in a physical experiment (in pulsed solenoids) does not exceed 10 2 T. Due to their small size, the rotation speed of neutron stars can reach 1000 Hz. Such a rapidly rotating magnetic star induces a vortex electric field around itself. This field accelerates the particles of the surrounding plasma to high energies. Nuclei root up to 10 20 eV, electrons - up to 10 12 eV. Having left the pulsar, these fast particles replenish the composition of the PCR.

Charged particles flying from space into the pulsar's magnetic field twist around the lines of force, emitting synchrotron radiation in the radio range. This radiation is especially strong in the direction of the magnetic poles. Since the axis of rotation of the pulsar does not coincide with the magnetic axis, the beam of radio emission describes a cone. If the Earth is in the wall of this cone, then a signal is periodically recorded on it at the moment when the polar beam of radio emission crosses the Earth.

Due to the loss of energy, the period of the pulsars increases. Therefore, the younger the pulsar, the higher its rotation frequency. Currently, several hundred pulsars are known, their periods from 0.033 s to 4.8 s.

Kvazary(abbreviated from the English quasi-stellar radio source) - quasi-stars, similar to stars. They are similar to stars in optical appearance and similar to nebulae in the nature of their spectra. In the spectra of quasars, a huge redshift is observed, 2-6 times higher than the largest known in the Galaxy. In the visible range, for example, the head UV line of the Lyman series is observed (D = 121.6 nm in the frame of reference of the emitting gas).

Having determined by the formula of the Doppler frequency shift ν = ν 0 √ ((1 ± β) / (1- + β)), where β = υ / s, the radial velocity υ of the quasar relative to the Earth, and using the empirical Hubble law υ = Нr, where H = 1.3-10 -18 s -1 is the Hubble constant, the distance to the quasar can be calculated. The distances to the quasar turned out to be gigantic. Their order is r ~ 10 10 ps. This is a million times the size of our Galaxy. The brightness of quasars changes with a period T of about 1 hour. Since the diameter of a quasar cannot exceed c * T, where c is the speed of light in vacuum, it turns out that the size of quasars is small, no more than the diameter of the orbit of Uranus (4 * 10 12 m). Taking into account the great remoteness of quasars, it turns out that they should emit a gigantic power of the order of 10 45 W, comparable to Galaxies, in a relatively small volume of space. Such super-powerful objects must eject streams of high-energy particles into space. The energy mechanism of quasars is unclear. With such a huge energy consumption, the active stage of quasars should be limited to 10 thousand years. To date, about 200 optical objects are considered quasars.

4. Solar cosmic rays. The sun is the closest star to Earth. This star is in a stationary state and, therefore, is not a noticeable source of PCR on the scale of the Galaxy. But since the Earth is very close to the Sun, it is within the reach of the plasma flowing from the Sun - the solar wind. The solar wind consists of protons and electrons. It originates in ascending gas-dynamic flows - torches in the photosphere layer and develops in the chromosphere.

The energy of the particles of the solar wind, but in comparison with galactic rays, is very small: for electrons E ≈ 10 4 eV, for protons no more than 10 11 N eV. During the activation of explosive processes on the surface of the Sun (the period of solar activity), the concentration of particles in the solar wind in the Earth's orbit is hundreds of times higher than the concentration of particles in galactic rays. Therefore, the influence of the solar wind on terrestrial processes during the period of solar activity is much more noticeable in comparison with galactic rays. At this time, radio communication is disrupted, geomagnetic storms and auroras occur. But on average, the contribution of solar cosmic rays to the Earth is small. It is 1-3% in intensity.

5. Secondary cosmic rays is a flux of particles generated during the interaction of PCR with the material of the Earth's atmosphere. Often, the passage of a particle in a substance is characterized by its average range l before interacting with the nucleus of the medium. Often, the average run is expressed by the mass of a substance in a column with an area of ​​1 cm 2 and a height l. So, the entire thickness of the earth's atmosphere is 1000 g / cm 2. For protons, the range l corresponds to 70-80 g / cm 2, for α-particles - 25 g / cm 2, for heavier nuclei this value is even less. The probability of a proton reaching the earth's surface is found from Bouguer's law. I / I 0 = exp (-x / l) = exp (-1000/70) ≈10 -7. Of the 10 million primary protons, only one will reach the Earth. For α-particles and nuclei, this number is even smaller. In secondary cosmic rays, 3 components are distinguished: nuclear-active (hadronic), hard (muonic) and soft (electron-photon).

a. Nuclear active component contains protons and neutrons arising from the interaction of protons and other high-energy PCR particles E 0> 1 GeV with the nuclei of atoms of the earth's atmosphere, mainly nitrogen N and oxygen O. When a particle hits the nucleus, about half of its energy is spent on knocking out several nucleons with energies E≈0.2 GeV, for the excitation of the final nucleus and for the multiple production of relativistic particles. These are mainly peonies π +, π 0, π -. Their number per primary proton with energy E 0 ≈0.2 GeV can reach 10. An excited nucleus decays and emits several more nucleons or α-particles. Nascent nucleons and a primary particle, interacting with the nuclei of the atmosphere, lead to the development of a nuclear cascade. The protons and other low-energy infected particles appearing in each act of collision are rapidly decelerated and absorbed as a result of ionization losses. Neutrons also participate in the further multiplication of nuclear-active particles down to the lowest energies.

b. Rigid (muon) component is born in a nuclear cascade of charged pions with energy Е≤100 GeV, decaying according to the scheme: π ± → μ ± + ν μ (ṽ μ), where μ ± are charged muons. Their rest mass is 207m e, and the average lifetime in their own reference frame is τ 0 = 2 * 10 6 s; ν m (ṽ m) - muonic neutrino (antineutrino). Muons, in turn, decay according to the scheme: μ - → e - * ṽ, μ + → e + * ν. Since the velocities of muons are close to the speed of light, then, in accordance with the theory of relativity, the average time of their life in the frame of reference connected with the Earth turns out to be quite large. As a result, muons have time to traverse the entire atmosphere and even about 20 m of soil. This is also due to the fact that muons and even more so neutrinos interact weakly with matter. That is why the flux of muons and neutrinos is called the hard or penetrating component of secondary cosmic rays.

e. Soft (electron-photon) component. Its main source is neutral pions π 0, formed in a nuclear collision. Compared to charged pions π + and π -, whose lifetime is 2 * 10 -6 s, neutral pions decay faster, their average lifetime is τ = 1.8 * 10 -16 s. From the place of its birth, the π 0 -pion manages to leave a negligible distance x≈c * τ = 3 * 10 8 * 1.8 * 10 -16 = 5 * 10 -8 m and decays into two high-energy γ-quanta: π0 → γ + γ. These energetic γ-quanta in the field of nuclei decay into electron-positron pairs, γ → e - + e +. Each of the generated electrons has a high velocity and, upon collision with nuclei, emits bremsstrahlung γ-quanta, e - → e - + γ .. Etc. An avalanche-like process arises.

The increase in the number of electrons, positrons and γ-quanta will continue until the energy of the particles decreases to 72 MeV. After this, the predominant energy losses are due to the ionization of atoms in the particles and to the Compton scattering in the γ-quanta. The increase in the number of particles in the shower stops, and its individual particles are absorbed. The maximum development of the soft component occurs at an altitude of about 15 km.

At very high energies of primary particles E 0>. 10 5 GeV electron-photon cascade avalanches in the earth's atmosphere acquire the specific features of extensive air showers. The development of such a shower begins at an altitude of 20-25 km. The total number of particles can reach 10 8 -10 9. Since one particle in the shower has an energy of approximately 1 GeV, the energy of the primary particle can be estimated from the number of particles in the shower.

The existence of such cascade showers was discovered in 1938 by the Frenchman Pierre Auger. Therefore, they are often called Auger showers.