Dark matter in the universe. Baryon Dark Mattery

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Dark matter Dark not because black, but because it is a "dark horse" in the literal sense: no one knows what it is. Physics dark matter is needed in order to explain the discrepancy in accelerating the expansion of the universe and the inconsistency of the visible mass of matter. Dark matter takes over 95% invisible matter from all its number in the universe. The problem is that dark matter is weakly interacting with real Mir, only at the gravity level, so catch, fix or create it is not possible on this moment. And our means of monitoring and searching are too weak to catch particles of dark matter, although work in this area is definitely underway.

The European Laboratory of Physical Research of CERN stated that it is planning a new experiment to find particles associated with dark matter, which is assumed to be about 27% of the Universe. The experiment will be conducted in the same place where a giant laboratory in a 27-kilometer tunnel on the French-Swiss border is located. Its task will be the search for "lungs and weakly interacting particles".

The universe consists of only 4.9% of the usual substance - the Baryon matter, from which our world consists. Most of 74% of the entire universe falls on mysterious dark energy, and 26.8% of the mass in the universe falls on non-liable physical laws, difficult to detect particles called dark matter.

This strange and unusual concept of dark matter has been proposed in an attempt to explain inexplicable astronomical phenomena. So there is some kind of existence powerful energy, so dense and massive - it is five times more than a conventional matter of matter, from which our world consists, we are, scientists spoke after the detection of incomprehensible phenomena in the gravity of stars and the formation of the universe.

Where did the concept of dark matter come from?

So, the stars in the spiral galaxies like ours, have a rather high rate of treatment and in all the laws with such a fast movement should simply fly out into the intergalactic space, like oranges from the overturned basket, but they do not do it. They hold them some strongest gravitational force, which is not registered and is not captured by any of our ways.

Another interesting confirmation of the existence of some dark matter scientists received from the research of the cosmic microwave background. They showed that after the large explosion, the matter at the very beginning was homogeneous distributed in space, but in some places its density was slightly higher than on average. These areas have a stronger gravity, unlike those surrounded, and at the same time, attracting matter to themselves, they became even dense and massive. This whole process was to be too slow, in order for only 13.8 billion years, (and this is the age of the universe), form major galaxies, including our Milky Way.

Thus, it remains to be assumed that he accelerates the pace of development of galaxies, the presence of a sufficient amount of dark matter with its additional gravity, significantly accelerating this process.

What is she - Dark Mature?

One of the central ideas that Black Matter consists of still not open subatomic particles. What kind of particles and who claims to have a lot of candidates.

It is assumed that fundamental elementary particles Farmion family has supersymmetric partners from another family - bosons. Such weak-inactive massive particles are named Wimp (or simply VIPs). The easiest and easiest of the stable superpartner is neutralino. Here he is, he is the most likely candidate for the role of the substances of dark matter.

At the moment, attempts to get neutralino or at least similar or at all a different particle of dark matter did not lead to success. Samples of obtaining neutralino were taken on ultra-high-energy clashes on gaining fame and different assessment by a large hadron collider. In the future, experiments will be carried out with even greater collision energies, but this does not guarantee that at least some models of dark matter will be detected.

As Matthew McCalow says (from the center of theoretical physics of the Massachusetts Technological Institute) - "Our ordinary world is designed difficult, it is not built from the same type of particles, and if the dark matter is also complicated?". According to his theory, hypothetically dark matter can interact with himself, but at the same time ignore ordinary matter. That is why we cannot see and somehow register its presence.

(Map of Space Microwave Background (CMB) made by Wilkinson Microwave Anisotropy Probe (WMAP))

Our galaxy Milky Way consists of a huge scale of the spherical rotating clouds of dark matter, it is mixed with a small number of ordinary matter, which is compressed under the action of gravity. It happens faster between poles, not as in the equator area. As a result, our galaxy acquires a look of a flattened spiral disc from stars and immersed in a spheroidal cloud of dark matter.

Theories of the existence of dark matter

To explain the nature of the missing mass in the Universe, various theories were put forward, one way or another, speaking on the existence of dark matter. Here is some of them:

The gravitational attraction of the usual registered matter in the Universe cannot explain the strange movement of stars in galaxies, where in the external areas of spiral galaxies of the stars are treated so quickly that they would simply be flying out into the interstellar space. What keeps them, if it is impossible to fix.
The existing dark matter exceeds the usual matter of the universe of 5.5 times and only its additional gravity can explain the uncharacteristic movements of stars in spiral galaxies.
Possible particles of dark matter VIMPs (WIMP), they are weak-sewing massive particles. In this case, descended supersymmetric partners of subatomic particles. In theory there are over three spatial measurements inaccessible to us. The complexity is to register them when additional measurements on Kaluzy-Klein theory are inaccessible for us.

Perhaps whether to register dark matter?

Through the land, there are huge number of particles of dark matter, but since dark matter does not interact, and if there is interaction, it is extremely weak, almost zero, with ordinary matter, then in most experiments there were no significant results.

Nevertheless, attempts to register the presence of dark matter are trying in the experiments of the collision of various atomic nuclei (silicon, xenon, fluorine, iodine and others) in the hope of seeing the return from the particles of dark matter.

In the Neutrino Astronomical Observatory at the Amundsen station - Scott with an interesting name IceCube research on the detection of high-energy neutrinos born outside the solar system.

Here on the south pole, where the temperature overboard up to -80 ° C, high-precision electronics is installed at a depth of 2.4 km, ensuring a continuous process of observing the mysterious processes of the universe, occurring beyond the edge of ordinary matter. While this is only attempts to come close up to the adequate secrets of the Universe, but some successes are already there, such as the historical discovery of 28 neutrinos.

So. It is incredibly interesting that the Universe, consisting of dark matter, inaccessible to the visible study by us may be many times more complicated by the device of our universe. And perhaps, the universe of dark matter significantly exceeds our and precisely there are all important things, the echoes of which we are trying to see in our ordinary matter, but it is already moving to the science fiction area.

All that we see around ourselves (stars and galaxies) is not more than 4-5% of the entire mass in the universe!

According to the cosmological theories of modernity, our universe consists of only 5% of the usual, the so-called baryon matter, which forms all observed objects; 25% of dark matter registered due to gravity; and dark energy components of as much as 70% of the total.

Terms Dark energy and dark matter are not quite successful and represent a literal, but not a semantic translation from English.

In the physical sense, the terms of the terms meant, only the fact that these substances do not interact with photons, and with the same success could be called invisible or transparent matter and energy.

Many modern scientists are convinced that research aimed at studying dark energy and matter is likely to help get an answer to the global question: what does our universe expects in the future?

Bush size with galaxy

Dark matter is a substance consisting, most likely, from new, still unknown particles and having properties inherent in the most ordinary substance. For example, it is also capable of both conventional substances to gather in the clots and participate in gravitational interactions. That's just the dimensions of these so-called bunches can exceed the whole galaxy or even accumulation of galaxies.

Approaches and methods for studying particles of dark matter

At the moment, scientists of the whole world are in every way to detect or obtain artificially on earthly particles of dark matter, through specially developed extensive equipment and many different research methods, but so far all the works are not crowded with success.

One method is associated with experiments on high-energy accelerators, widely known as colliders. Scientists, believing that the dark matter particles are harder than the proton 100-1000 times, it is assumed that they will have to be born in the collision of ordinary particles, overclocked to high energies through a collider. The essence of another method is to register particles of dark matter, which are everywhere around us. The main complexity of registration of these particles is that they show very weak interaction with conventional particles, which are inherently for them as transparent. And yet, particles of dark matter very rarely, but face atomic nuclei, and there is a certain hope sooner or later still register this phenomenon.

There are other approaches and methods for studying particles of dark matter, and which one will first lead to success, will show only time, but in any case, the opening of these new particles will become the most important scientific achievement.

Antigravitation substance

Dark energy is an even more unusual substance than the same dark matter. It does not have the ability to gather in the clots, as a result of which it is evenly distributed absolutely throughout the universe. But the most unusual property is currently anti-gravity.

Nature of dark matter and black holes

Thanks to modern astronomical methods, it is possible to determine the rate of expansion of the Universe at present and simulate the process of its change earlier in time. As a result, information was obtained that at the moment, as well as in the nearby past, our universe expands, while the pace of this process is constantly increasing. That is why there was a hypothesis about the anti-gravity of the dark energy, since the usual gravitational attraction would have a slowing effect on the process of "galaxies' running", while holding back the expansion rate of the universe. This phenomenon does not contradict the general theory of relativity, but at the same time, dark energy must be possessing negative pressure - a property that does not have one of the currently known substances.

Candidates for the role of "Dark Energy"

The mass of galaxies in the accumulation of Abel 2744 is less than 5 percent of all its mass. This gas is so hot that shines only in the X-ray range (red in this image). The distribution of invisible dark matter (component of about 75 percent of the mass of this cluster) is painted in blue.

One of the alleged candidates for the role of dark energy is a vacuum, the energy density of which remains unchanged in the process of expanding the universe and confirms the negative pressure of the vacuum. Another estimated candidate is the "quintessence" - an uncharted super-timber field, allegedly passing through the entire universe. There are also other possible candidates, but not one of them at the moment did not contribute to obtaining an accurate answer to the question: what is dark energy? But it is already clear that dark energy represents something completely supernatural, remaining the main mystery of the fundamental physics of the XXI century.

Introduction

There are weighty arguments in favor of the fact that a significant part of the substance in the universe does not radiate and does not absorb and therefore invisible. We can learn about such invisible matter in its gravitational interaction with radiating matter. The study of clusters of galaxies and galactic rotary curves indicates the existence of this so-called dark matter. So, by definition, dark matter is matterium, which does not interact with electromagnetic radiation, that is, does not empty it and does not absorb it.
The first detection of invisible matter is dated last century. In 1844, Friedrich Bessel in writing to Karl Gaussu wrote that the unexplained unevenness in the movement of Sirius could be the result of its gravitational interaction with some neighboring body, and the latter in this case should have a sufficiently large mass. In the time of Bessel, such a dark companion of Sirius was invisible, it was optically discovered only in 1862. They turned out to be a white dwarf, called Sirius-B, while Sirius himself was named Sirius.
The density of the substance in the universe ρ can be estimated from the observations of the movement of individual galaxies. Usually ρ is given in units of the so-called critical density ρ C:

In this formula G - gravitational constant, H is a permanent Hubble, which is known with a small accuracy (0.4< H < 1), к тому же, вероятно, зависит от времени:

V \u003d HR - Formula Hubble for the expansion rate of the Universe,
H \u003d 100 H km ∙ C -1 ∙ MPS -1.

For ρ\u003e ρ with the universe is closed, i.e. Gravitational interaction strongly so that the expansion of the universe has changed with compression.
Thus, the critical density is given by the expression:

ρ C \u003d 2 ∙ 1 -29 H 2 g ∙ cm -3.

The cosmological density ω \u003d ρ / ρ C, determined on the basis of the dynamics of galactic clusters and supercluster, is 0.1< Ω < 0.3.
From the observation of the nature of the removal of large-scale areas of the Universe with the help of an infrared astronomical satellite IRAS, it was obtained that 0.25< Ω < 2.
On the other hand, the assessment of the baryon density ω b for the luminosity of galaxies gives a significantly smaller value: Ω b< 0.02.
This mismatch is usually considered as an indication of the existence of invisible matter.
Recently, the problem of finding dark matter has become very much attention. If we take into account all the forms of baryon matter, such as interplanetary dust, brown and white dwarfs, neutron stars and black holes, it turns out that there is a significant proportion of non-bairionic matter to explain all the observed phenomena. This statement remains in force even after taking into account modern data on the so-called Macho objects ( MA.ssive. C.ompact. H.alo. O.bJECTS - massive compact galactic objects) detected using the effect of gravitational lenses.

. Evidence of the existence of dark matter

2.1. Galactic rotary curves

In the case of spiral galaxies, the speed of rotation of individual stars around the center of the Galaxy is determined from the condition of the constancy of orbits. Equating centrifugal and gravitational forces:

for rotation speed, we have:

where M R is the whole mass of matter within the range of R radius. In the case of an ideal spherical or cylindrical symmetry, the effect of mass located outside this sphere is mutually compensated. In the first approximation, the central region of the galaxy can be considered a spherical, i.e.

where ρ is the average density.
In the inside of the galaxy, a linear increase in the speed of rotation with increasing distance from the center is expected. In the outer region of the galaxy, the mass M r is almost constant and the dependence of the speed from distance is in case of a point in the center of the Galaxy:

The rotational velocity V (R) is determined, for example, by measuring the Doppler shift in the radiation spectrum of the HE-II regions around the O stars. The behavior of experimentally measured rotary curves of spiral galaxies does not correspond to a decrease in V (R) with increasing radius. The study of the 21-cm line (the transition of the hyperfine structure in the hydrogen atom) emitted by the interstellar substance led to a similar result. The constancy V (R) at large radius values \u200b\u200bmeans that the mass M R is also increasing with increasing radius: M R ~ R. This indicates the presence of invisible matter. Stars are moving faster than it was possible to expect on the basis of the visible number of matter.
Based on this observation, the existence of a spherical halo of dark matter surrounding the galaxy and responsible for the inconsiderable behavior of rotary curves was postulated. In addition, spherical halo could contribute to the stability of the Galaxian disk form and confirm the hypothesis on the formation of galaxies from spherical protoglactics. Model calculations made for the Milky Way with which they managed to reproduce rotary curves, taking into account the presence of halo, indicate that a significant part of the mass should be in this halo. Certificates for the existence of spherical halo are also given globular clusters - spherical accumulations of stars, which are the most ancient objects in the galaxy and which are distributed spherically.
However, the recent study of the transparency of the Galaxy threw the shadow of doubts about this picture. By considering the degree of darlicity of spiral galaxies as the function of an angle of ignition, it is possible to conclude about the transparency of such objects. If the galaxy was completely transparent, then its full luminosity would not depend on the corner, under which this galaxy is observed, since all stars would be the same in the same way (in neglect of the sizes of stars). On the other hand, a constant surface brightness means that the galaxy is not transparent. In this case, only external stars see the observer, i.e. Always the same thing for the unit surface, regardless of the angle of view. It was experimentally established that the surface brightness remains on average constant, which could indicate the almost complete opacity of spiral galaxies. In this case, use optical methods To determine the mass density of the universe is not exactly accurate. A more careful analysis of measurement results led to the conclusion of molecular clouds as an absorbent material (their diameter of about 50 ps and a temperature of about 20 K). According to the law of wing bias, such clouds should emit in the submillimeter region. This result could give an explanation of the behavior of rotary curves without assumption of additional exotic dark matter.
Certificates for the existence of dark matter were found in elliptical galaxies. Gaseous halo with temperatures of about 10 7 K were recorded by their absorption of X-rays. The speed of these gas molecules is greater than the expansion speed:

v r \u003d (2gm / r) 1/2,

if you assume that their masses correspond to the luminosity. For elliptic galaxies, the mass attitude to the luminosity is about two orders of magnitude more than the sun, which is a characteristic example of a middle star. Such great importance is usually associated with the existence of dark matter.

2.2. Dynamics of clusters of galaxies

The dynamics of clusters of galaxies evidenced in favor of the existence of dark matter. When the movement of the system, the potential energy of which is a homogeneous function of coordinates, occurs in a limited spatial region, then the time-averaged values \u200b\u200bof the kinetic and potential energy are connected with each other the virique theorem. It can be used to assess the density of the substance in the clusters big number galaxies.
If the potential energy U is a homogeneous function of radius vectors r. I degrees k, then u and kinetic energy T are associated as 2t \u003d ku. Since t + u \u003d e \u003d e, then it follows that

U \u003d 2e / (k + 2), t \u003d Ke / (k + 2),

where E is complete energy. For gravitational interaction (U ~ 1 / R) k \u003d -1, therefore 2t \u003d -u. The average kinetic energy of the cluster N galaxies is given by the expression:

T \u003d N. /2.

These N galaxies can interact in pairs with each other. Therefore, there are N (N-1) / 2 independent pairs of galaxies, the total average potential energy of which is

U \u003d Gn (n - 1) M 2 / 2R.

For nm \u003d m and (n - 1) ≈ n, M ≈ 2 is obtained for dynamic mass / G.
Middle Distance Measurements and medium speed The value of the dynamic mass, which is about two orders of magnitude exceeds the mass obtained on the basis of the analysis of the luminosity of galaxies. This fact may be interpreted as another evidence in favor of the existence of dark matter.
This argument also has its weaknesses. The virial equation is valid only when averaging at a long time period, when closed systems are in a state of equilibrium. However, the measurements of galactic clusters are something like instant photographs. Moreover, the accumulations of galaxies are not closed systems, they are connected with each other. Finally, it was not clear, they reached the status of equilibrium or not.

2.3. Cosmological evidence

The above was given to the definition of the critical density ρ s. Formally, it can be obtained based on Newtonian dynamics by calculating the critical expansion rate of spherical galaxy:

The ratio for ρ C follows from an expression for e if we take that H \u003d R "/ R \u003d V / R.
Description of the dynamics of the Universe is based on the field equations of Einstein (the overall theory of relativity is from). They are somewhat simplified under the assumption of homogeneity and isotropy of space. In a metric Robertson-Walker, an infinitezimal linear element is given by expression:

where R, θ, φ is spherical coordinates of the point. The degrees of freedom of this metric are included in the parameter K and a large-scale multiplier R. The value of K only discrete values \u200b\u200b(if not to take a fractal geometry in consideration) and does not depend on time. The value K is the characteristic of the universe model (k \u003d -1 - hyperbolic metric (open universe), k \u003d 0 - Euclidean metric (flat universe), k \u003d +1 - spherical metric (closed universe)).
The dynamics of the universe fully sets the scale function R (T) (the distance between two adjacent points of space with the coordinates R, θ, φ changes with time as R (T)). In the case of a spherical metric R (T) is the radius of the universe. This large-scale function satisfies Einstein-Friedman-Lemeter equations:

where P (T) is a complete pressure, and λ is a cosmological constant, which within the framework of modern quantum-field theories is interpreted as a vacuum energy density. Next, assume that λ \u003d 0, as is often done to explain experienced facts without the introduction of dark matter. The ratio R 0 "/ R 0 determines the Hubble H 0 constant, where the index" 0 "is noted by modern values \u200b\u200bof the corresponding values. Of the above formulas, it follows that for the parameter of the curvature k \u003d 0, the modern critical density of the universe is given by the expression, whose value is the boundary between the open and a closed universe (this value as it is separated by the script in which the Universe is always expanding, from that scenario when the universe expects a collapse at the end of the temporary expansion phase):

Frequently used density parameter

where Q 0 is the braking parameter: Q (T) \u003d -R (T) R "" (T) / (R "(T)) 2. Thus, three cases are possible:
Ω 0 < 1 − открытая Вселенная,
Ω 0 \u003d 1 - flat universe,
Ω 0\u003e 1 - closed universe.
The measurements of the density parameter were estimated: ω 0 ≈ 0.2, on the basis of which the open nature of the universe should be expected. However, a number of theoretical ideas are difficult to coordinate with the openness of the universe, for example, the so-called "flatness" problem and the genesis of galaxies.

The problem of flatness

As can be seen, the density of the universe is very close to the critical. From Einstein-Friedman-Lemeter equations (at λ \u003d 0), which

Since the density ρ (t) is proportional to 1 / R (T) 3, then using the expression for ω 0 (K not equal to 0) we have:

Thus, the value ω ≈ 1 is very unstable. Any deviation from a completely flat case is greatly increasing as the universe expands. This means that during the initial nuclear synthesis The universe was to be much more flat than now.
One of possible solutions This problem is given in inflation models. It is assumed that the expansion of the early universe (in the interval between 10 -34 s and 10 -31 s after a large explosion) was exponentially in the inflation phase. In these models, the density parameter is usually independent of time (ω \u003d 1). However, there are theoretical instructions on the fact that the value of the density parameter in the range of 0.01< Ω 0 < 2 также согласуется с моделью инфляции.

Genesis Galaktik

For the genesis, galaxies are needed by density heterogeneity. The galaxies were to arise in such spatial areas where densities were more than around, so as a result of gravitational interaction, these areas have time to clutter faster than their perisions due to universal expansion.
However, this type of matter accumulation could begin only after the formation of atoms from nuclei and electrons, i.e. Approximately 150,000 years after a large explosion at temperatures about 3000 K (since in the early stages, the substance and radiation were in a state of dynamic equilibrium: any form of cloth of matter immediately destroyed under the influence of radiation and at the same time radiation could not break out of matter ). Noticeable fluctuations of the density of ordinary matter at that time were excluded up to a very low level of isotropy of background radiation. After the stage of formation of neutral atoms, radiation ceases to be in a state of thermal equilibrium with matter, thereby occurring after this fluctuation of the density of matter do not find more reflected in the radiation character.
But if you calculate the evolution in the time of the process of compression of matter, which just started, it turns out that the time has passed since then it is not enough to have such large structures such as galaxies or their clusters. Apparently, it is necessary to require the existence of massive particles that have come out of the state of thermal equilibrium at an earlier stage, so that these particles have the opportunity to show themselves as some embryos for condensation around them ordinary matter. Such candidates may be the so-called WIMP particles. At the same time, it is necessary to take into account the requirement of the isotropy of background ospace radiation. Small anisotropy (10 -4) in relic emission (about 2.7 k) was discovered only recently using a Cobe satellite.

III. Candidates for the role of dark matter

3.1. Baryon Dark Mattery

The most obvious candidate for the role of dark matter can be the usual baryon matter, which does not radiate and has the appropriate prevalence. One of the opportunities could be implemented by interstellar or intergalactic gas. However, in this case, characteristic lines of radiation or absorption that are not detected should occur.
Another candidate may be brown dwarfs - space bodies With the masses are significantly less than the mass of the sun (m< 0.08M солнца). Гравитационного давления внутри этих объектов оказывается недостаточно для создания температур, при которых начинает процесс слияния протонов в гелий. Из-за отсутствия ядерного синтеза излучение коричневых карликов очень слабо, если не считать излучения тех из них, которые находятся на ранней стадии своего развития. Планеты также могли бы входить в эту группу. Однако из-за отсутствия знания о происхождении звезд и планет, а также из-за ограниченности фотометрической детектируемости heavenly Tel The distance to several light years is especially difficult to assess the number of such objects.
Very compact objects that are at the final stages of the development of stars (white dwarfs, neutron stars and black holes) could also be part of the dark matter. Since during its lifetime, almost every star reaches one of these three finite stages, a significant part of the mass of earlier and more severe stars should be present in a non-forming form in the form of white dwarfs, neutron stars or black holes. Some of this substance returns to the interstellar space by outbreaks of supernova or other paths and takes part in the formation of new stars. It should not take into account the stars with the masses M< 0.9M солнца, так как их время жизни больше, чем возраст Вселенной, и они еще не достигли конечных стадий в своем развитии.
The upper boundaries on the possible density of the baryon matter in the Universe can be obtained from the data on the initial nuclear synthesis, which began approximately 3 minutes after the large explosion. Especially important measurements of the modern prevalence of deuterium -
(D / H) 0 ≈ 10 -5, since during the initial nuclear synthesis was the formation mainly was the deuterium. Although deuterium also appeared later as an intermediate product of the core merger reactions, nevertheless the total amount of deuterium was not increased due to this. Analysis of the processes occurring at the stage of early nuclear synthesis gives the upper boundary - Ω O, B< 0.1–0.2 для плотности возможной барионной материи во Вселенной. При этом учтена вся материя, которая была сформирована во время ядерного синтеза в ранней Вселенной. Данное значение хорошо согласуется с оценками, полученными из рассмотрения характера вращения галактик.
On the other hand, it is now quite clear that the baryon matter itself is not able to satisfy the requirement ω \u003d 1, which follows from inflationary models. In addition, the problem of the formation of galaxies remains unresolved. All this leads to the need for the existence of non-darium dark matter, especially in the case when the conditional satisfaction is required at zero cosmological constant.

3.2. Non-darium dark matter

Theoretical models provide a large selection of possible candidates for the role of non-darium dark matter, including: light and heavy neutrinos, suysymmetrical particles of SUSY-models, acion, cosmines, magnetic monopolis, Higgs particles - they are reduced in the table. The tables also present theories explaining the experimental data without the introduction of dark matter (time-dependent gravitational constant in nonenhane gravity and cosmological constant). Designations: DM - Dark matter, GUT - the theory of great association, SUSY - SuperSymmetric theories, sugra - supergravity, QCD - Quantum chromodynamics, QED - Quantum electrodynamics, from the general theory of relativity. The concept of WIMP (weak-to-absorbing massive particles) is used to designate particles with a mass of more than several GeV / C 2, which take part in weak interaction. Given the new measurements of relict radiation from the Cobe satellite and red bias using the IRAS satellite recently, a study of the distribution of galaxies at large distances and the formation of large-scale structures in our galaxy was recently. Based on the analysis of various models of the formation of structures, conclusion was made that only one satisfactory model of the universe with ω \u003d 1 is possible, in which dark matter has a mixed nature: 70% exists in the form of cold dark matter and 30% in the form of hot dark matter, and the latter It consists of two massless neutrinos and one neutrino with a mass of 7.2 ± 2 eV. This means the revival of the previously discarded model of mixed dark matter.

Light neutrinos

Unlike all other candidates for the role of dark matter, neutrinos have a clear advantage: it is known that they exist. Approximately known their prevalence in the universe. In order for neutrino to be candidates for the role of dark matter, they undoubtedly must have a mass. To achieve the critical density of the universe mass, neutrino must lie in the region of several GeVs / C 2 or in the region from 10 to 100 eV / C 2.
Heavy neutrinos are also possible as such candidates, since the cosmologically significant product M ν exp (-m ν / kt f) becomes small for large masses. Here T F is the temperature at which heavy neutrinos cease to be in a state of thermal equilibrium. This Boltzmann factor gives the prevalence of neutrino with a mass M ν in relation to the prevalence of mass-neutrino.
For each type of neutrinos in the universe, the neutrino density is associated with photon density by the relation N ν \u003d (3/11) N γ. Strictly speaking, this expression is valid only for light major neutrinos (for Dirakov neutrinos under certain circumstances, it is necessary to introduce another statistical factor equal to two). Photon density can be determined based on the background relict 3 to radiation and reaches N γ ≈ 400 cm -3.

Particle	Weight	Theory	Manifestation
G (R)	-	Nengetonova gravitization	Transparent DM on a large scale
Λ (space constant)	-	OTO	Ω \u003d 1 without DM
Aksion, Majoron, Goldstone. Boson	10 -5 EV	QCD; Violation of sim. Kuina prints	Cold DM.
Normal neutrino	10-100 EV	Gut.	Hot DM.
Easy Higgsino, Fotino, Gravitino, Axino, Snaithrino	10-100 EV	SUSY / DM.
Paraphoton	20-400 EV	Modifits. QED	Hot, warm DM
Right neutrinos	500 EV	Superlab interaction	Warm DM.
Gravitino, etc.	500 EV	SUSY / Sugra.	Warm DM.
Fotinos, gravitino, axion, mirrors. Particles, neutrino Simpson	keV	SUSY / Sugra.	Warm / Cold DM
Fotinos, Snahrino, Higgsino, Gluchiano, Heavy Neutrinos	MeV	SUSY / Sugra.	Cold DM.
Shadow matter	MeV	SUSY / Sugra.	Hot / cold (like Barione) DM
Precon	20-200 TV.	Composite models	Cold DM.
Monopoli	10 16 GeV	Gut.	Cold DM.
Pirgon, Maximon, Pole Perry, NewTorite, Schwarzshild	10 19 GeV.	Theories of the highest dimensions	Cold DM.
Superast	10 19 GeV.	SUSY / Sugra.	Cold DM.
Quark "nuggets"	10 15 g	QCD, Gut.	Cold DM.
Cosm Strings, domain walls	(10 8 -10 10) M Sun	Gut.	The formation of galaxies may not give a large contribution to
Cosmion	4-11 GeV.	Neutrino problem	Formation of the thread of neutrino in the sun
Black holes	10 15 -10 30 g	OTO	Cold DM.

Primak J.R., SECKEL D., Sadoulet B., 1988, Ann. Rev. NUCL. Part.sci., 38, 751 It turns out that the mass density of neutrinos is obtained close to the critical if the condition is performed

where G ν is a statistical factor that takes into account the number of different spirits for each type of neutrino. For mayorano neutrinos, this multiplier is 2. For Dirac neutrinos, it should be equal to 4. However, it is usually considered that the right components left the state of thermal equilibrium much earlier, therefore it is also possible to consider that G ν \u003d 2 and for a Dirac case.
Since the neutrino density has the same order of the magnitude as the density of photons, it exists about 10 9 times more neutrino than bariones, so even a small mass of neutrinos could determine the dynamics of the universe. To achieve ω \u003d ρ ν / ρ C \u003d 1, neutrino mass M ν C 2 ≈ 15-65 eV / n ν is necessary, where N ν is the number of lung neutrino types. Experimental upper boundaries for masses of three known types of neutrino are as follows: M (ν e)< 7.2 эВ/c 2 , m(ν μ) < 250 кэВ/c 2 , m(ν τ) < 31 МэВ/c 2 . Таким образом, электронное нейтрино практически исключается в качестве кандидата на доминирующую фракцию темной материи. Экспериментальные данные для остальных двух типов нейтрино не столь критичны, так что мюонные и тау-нейтрино остаются среди возможных кандидатов. Нейтрино вышли из состояния термического равновесия примерно через 1 с после Большого Взрыва при температуре 10 10 К (что отвечает энергии 1 МэВ). В это время они обладают релятивистскими энергиями и тем самым считаются частицами горячей темной материи. Нейтрино также могут давать вклад в процесс формирования галактик. В расширяющейся Вселенной, в которой доминируют частицы массой m i , согласно критерию Джинса, та масса, которая может коллапсировать за счет гравитационных сил, равна

In the universe, where neutrinos dominate, the required compression ratio could be established at a relatively late stage, the first structures would correspond to the superers of galaxies. Thus, the accumulations of galaxies and galaxies could develop by fragmentation of these primary structures (Top-Down model). However, with this approach, problems arise when considering the formation of very small structures, such as dwarf galaxies. To explain the formation of a rather massive compression, the principle of Pauli for fermions is also required.

Heavy neutrinos

According to the data of LEP and SLAC relating to the precision measurement of the decay width Z 0 - boson, there are only three types of neutrinos and exclude the existence of heavy neutrinos up to the values \u200b\u200bof the mass of 45 GeV / C 2.
When neutrino with such large masses left the state of thermal equilibrium, they already had non-relativistic speeds, so they are called particles of cold dark matter. The presence of severe neutrinos could lead to early gravitational compression of matter. In this case, smaller structures would first form. The accumulations and supercoplation of galaxies would be formed later by accumulating individual groups of galaxies (Bottom-Up model).

Axes

Axions are hypothetical particles that arise in connection with the problem of CP violations in a strong interaction (θ-problem). The existence of such a pseudoscale particle is due to the violation of the chiral symmetry of the Kuina. Axion's mass is given by expression

Interaction with fermions and calibration bosons is described by the following connection constants:

Permanent decay of axiona f. A is determined by vacuum middle fields Higgs. As f. A is a free constant that can take any values \u200b\u200bbetween an electroweak and plank scale, then the possible values \u200b\u200bof the mass of axion are vary 18 orders. DFSZ-axions, directly interacting with electrons, and the so-called hadron accesses, which interact with electrons only in the first order of perturbation theory. It is usually believed that ackesions make up cold dark matter. So that their density does not exceed the critical one must have F. A.< 10 12 ГэВ. Стандартный аксион Печеи-Куина с F. A ≈ 250 GeV is already excluded experimentally, other options with smaller masses and, accordingly, large communication parameters are also significantly limited to a variety of data, primarily astrophysical.

SuperSymmetric particles

Most suymmetric theories contain one stable particle, which is a new candidate for the role of dark matter. The existence of a stable supersymmetric particle follows from the preservation of a multiplicative quantum number - the so-called R-parity, which takes the value of +1 for conventional particles, and -1 for their superpart mainers. It is r-parity conservation law. According to this law, the SUSY particle conservation can be formed only by pairs. SUSY particles can disseminate only on an odd number of SUSY particles. Consequently, the lightest supersymmetric particle should be stable.
There is an opportunity to disrupt the law of conservation of R-parity. The quantum number R is associated with the baryon number B and the lepton number l by the ratio R \u003d (-1) 3b + L + 2S, where the S-spin particles. In other words, the violation B and / or L can lead to disruption of r-parity. However, there are very rigid borders to be able to violate R-parity.
It is assumed that the lightest supersymmetric particle (LSP) does not take part in either electromagnetic, but in strong interaction. Otherwise, it would be connected with conventional matter and would be manifested at present as an unusual heavy particle. Then the prevalence of such an LSP, normalized by the prevalence of the proton, would result in equal to 10 -10 for strong interaction, and 10 -6 for electromagnetic. These values \u200b\u200bcontradict the experimental upper boundaries: N (LSP) / N (P)< 10 -15 - 10 -30 . Приведенные оценки зависят от масс и в this case Answer the masses of the mass 1 GeV< m LSP c 2 < 10 7 ГэВ. Поэтому был сделан вывод о том, что легчайшая SUSY-частица, помимо гравитационного взаимодействия, принимает участие только в слабом.
Among possible candidates for the role of the neutral lightest supersymmetric particle, there are Fotinos (S \u003d 1/2) and Zino (S \u003d 1/2), which are commonly called gejino, as well as Higgsino (S \u003d 1/2), Sneprino (S \u003d 0) and gravitino (s \u003d 3/2). In most, the LSP particle theories is a linear combination of the SUSY particles mentioned above with 1/2. The mass of this so-called neutralino is likely to be more than 10 GeV / C 2. Consideration of SUSY particles as dark matter is of particular interest, as they appeared completely in another context and were not specifically introduced to resolve the problem (non-bairion) dark matter. Cosmones Cosmians were originally introduced to solve the problem of solar neutrino. Thanks to high speed These particles pass through the surface of the star almost unhindered. In the central area of \u200b\u200bthe star they face the nuclei. If the energy loss is large enough, they cannot leave this star again and accumulate in it over time. Inside the Sun, the captured cosmines affect the nature of energy transmission and thereby contribute to the cooling of the central region of the Sun. This would lead to a lower likelihood of neutrino formation from 8 V and explained why the thread of neutrino measured on Earth turns out to be less than expected. To resolve this neutrino problem, the mass of the cosmone must lie in the range from 4 to 11 GeV / C 2 and the cross section of the reaction of the interaction of cosmones with matter should be 10 -36 cm 2. However, experimental data seems to eliminate such a solution to the problem of solar neutrino.

Topological defects space-time

In addition to the above particles, topological defects can also contribute to dark matter. It is assumed that in the early universe at T ≈ 10 -36 C, E ≈ 10 15, the GEV, T ≈10 28, there was a violation of GUT symmetry, which led to the disconnection of the interactions described by SU groups (3) and SU (2) × u (one). Higgs field with dimension 24 has acquired a certain extension, and the orientation of the phase angles of the spontaneous violation of symmetry remained arbitrary. As a result of this phase transition, spatial areas with different orientation were supposed to be formed. These areas have increased over time and eventually entered into contact with each other.
According to modern ideas Topologically stable defect points were formed on the boundary surfaces, where there was a meeting of areas with different orientation. They could have dimension from zero to three and consist of a vacuum of undisturbed symmetry. After the symmetry disorder, this initial vacuum has very large energy and the density of the substance.
The most important are spot-like defects. They must carry an isolated magnetic charge, i.e. Be magnetic monoplas. Their mass is associated with the phase transition temperature and is about 10 16 GeV / C 2. So far, despite the intensive searches, the existence of such objects is not registered.
Similar to magnetic monopulars can also form linear defects - cosmic strings. These thread-shaped objects have a characteristic linear mass density of about 10 22 g ∙ cm -1 and can be both closed and unlocked. Due to the gravitational attraction, they could serve as embryos for condensation of a substance, as a result of which galaxies were formed.
Mass solutions would allow to detect such strings through the effect of gravitational lenses. Strings would be twisted the surrounding space in such a way that a double image of objects behind them would be created. Light from very distant galaxies could deviate this string according to the laws of the general theory of gravity. Observer on Earth would see two adjacent mirror images of galaxies with identical spectral composition. This effect of gravitational lenses has already been detected for remote quasars when the galaxy between the quasar and the Earth served as a gravitational lens.
The possibility of the presence of a superconducting state in cosmic strings is also discussed. Electrically charged particles, such as electrons, in a symmetric vacuum of strings would be massless, because they acquire their masses only as a result of a symmetry disorder due to the Higgs mechanism. Thus, a pair of a particle-antiparticle, moving at the speed of light, can be created here at very low energy costs. As a result, the superconducting current occurs. Superconducting strings could move to an excited state by interacting with charged particles, the removal of this excitation would be carried out by emitting radio waves.
Defects are also considered, including two-dimensional "domain walls" and, in particular, three-dimensional defects or "textures". Other exotic candidates

Shadow matter.Under the assumption that strings are one-dimensional extended objects, attempts are being made in super terminal theories to repeat the success of supersymmetric models in the elimination of divergences also in gravity and penetrate the energy regions by the mass of the plank. From a mathematical point of view, super terminated theories can be obtained only for SO calibration groups (32) and E 8 * E 8. "The latter is split into two sectors, one of which describes ordinary matter, while the other corresponds to the shadow matter (E 8 "). These two sectors can interact with each other only gravitational.
"Quark nuggets"it was proposed in 1984. These are stable macroscopic objects from quark matter, consisting of U-, D- and S-quarks. The density of these objects lie in the nuclear density area of \u200b\u200b10 15 g / cm 3, and the masses can be from several GeVs / C 2 to the masses of the masses of neutron stars. They are formed in the hypothetical phase QCD transition, but are usually considered very unlikely.

3.3. Modified theories (cosmological constant, Mond-theory, time-dependent gravitational constant)

Initially, the cosmological constant λ was introduced by Einstein in the field equations from the OTO to ensure, according to the views of the time, the stationarity of the Universe. However, after the opening of the Hubble at the end of the 20s of our century, the expansion of the universe was excessive. Therefore began to assume that λ \u003d 0. However, within modern theories The fields of this cosmological constant is interpreted as a vacuum energy density ρ v. The following equation takes place:

The case λ \u003d 0 meets the assumption that the vacuum does not give a contribution to the energy density. This picture meets the ideas of classical physics. In the quantum and field theory, the vacuum contains various quantum fields that are in a state with the lowest energy, which is not at all is zero.
Taking into account the non-zero cosmological constant, with the help of relations

we obtain a smaller critical density and a greater value of the density parameter than expected according to the formulas above. Astronomical observations based on calculations of the number of galaxies, for the modern cosmological constant give the upper border
Λ < 3·10 -56 см –2 . Поскольку критическая плотность ρ с0 не может быть отрицательной, легко оценить верхнюю границу

where for H 0, MAX is used value of 100 km ∙ s -1 ∙ MPS -1. While the non-zero cosmological constant turned out to be necessary for the interpretation of the early phase of evolution, some scientists came to the conclusion that λ, not equal to 0, could play a role in the subsequent stages of the development of the universe.
Cosmological permanent size

it could lead to the value Ω (λ \u003d 0), although in fact Ω (λ ≠ 0). The parameter ω (λ \u003d 0), determined from ρ 0, would provide Ω \u003d 1, as required in inflationary models, provided that the cosmological constant is equal

The use of numerical values \u200b\u200bof H 0 \u003d 75 ± 25 km ∙ C -1 ∙ MPS -1 and ω 0, OBS \u003d 0.2 ± 0.1 leads to
Λ \u003d (1.6 ± 1.1) ∙ 10 -56 cm -2. The vacuum energy density corresponding to this value could solve the contradiction between the observed value of the density parameter and the required modern theories Ω \u003d 1.
In addition to the introduction of nonzero cosmological constant, there are other models that remove at least some of the problems without attracting dark matter hypothesis.

Mond Theory (Modified Newtonian Dynamics)

In this theory, it is assumed that the law of gravity differs from the usual Newtonian form and is as follows:

In this case, the attraction force will be more and must be compensated by a faster periodic movement, which is able to explain the flat behavior of rotary curves.

Gravitational constant, time-dependent

The dependence on the time of the gravitational constant G (T) could be of great importance for the process of formation of galaxies. However, until now, precision measurements did not give any instructions on the temporary variation of G.

Literature

G.V. Clapador Clangrothaus, A. Studt. "Unspatriary physics of elementary particles."
C. Naranjan. "General Astrophysics and Cosmology."
Bottino A. et al., 1994, Astropart. Phys., 2, 67, 77.

It is known that dark substance Interacting with "luminous" (baryonic), at least gravitational and represents a medium with an average cosmological density, several times greater than the density of barion. The latter are captured in gravitational pits of the concentrations of dark matter. Therefore, although particles of dark matter and do not interact with light, the light is emitted from there, where there is a dark substance. This wonderful property of gravitational instability made it possible to study the number, state and distribution of dark matter on observational data from the radio parason to X-ray radiation.

The direct study of the distribution of dark matter in the clusters of galaxies was made possible after receiving their highly detailed images in the 1990s. At the same time, the images of more remote galaxies that are projected into accumulation are distorted or even cleaved due to the effect of gravitational lenzing. By the nature of these distortion it becomes possible to restore the distribution and the magnitude of the mass inside the cluster, regardless of the observations of the galaxies of the cluster itself. Thus, the direct method is confirmed by the presence of hidden mass and dark matter in galactic clusters.

Published in 2012 studying the movement of more than 400 stars located at distances up to 13,000 light years from the Sun, did not find evidence of the presence of dark matter in large volume Space around the sun. According to the theory predictions, the average number of dark matter in the surroundings of the Sun should be about 0.5 kg in volume globe. However, the measurements were given a value of 0.00 ± 0.06 kg of dark matter in this volume. This means that attempts to register dark matter on Earth, for example, with rare interactions of dark matter particles with "ordinary" matter, can hardly be successful.

Candidates for the role of dark matter

Baryon Dark Material

It seems the most natural thing seems that dark matter consists of a conventional, baryon substance, for any reason a weakly interacting electromagnetic manner and therefore undisturbed during the study, for example, emission lines and absorption. The composition of the dark substance may include many already discovered space objects, like: dark galactic halo, brown dwarfs and massive planets, compact objects at the final stages of evolution: white dwarfs, neutron stars, black holes. In addition, such hypothetical objects, as quark stars, Q-stars and the preconnic stars may also be part of the Baryon Dark Matter.

The problems of this approach are manifested in the cosmology of a large explosion: if all the dark matter is represented by baryons, the ratio of the concentrations of light elements after the primary nucleosynthesis, observed in the oldest astronomical objects, should be different, sharply different from the observable. In addition, experiments on the search for gravitational linlication of light of the stars of our galaxy show that a sufficient concentration of large gravel objects such as planets or black holes to explain the mass of the halo of our galaxy is not observed, and small objects of sufficient concentrations should absorb the lights of the stars too much.