scholarly journals From the Early Universe to the Modern Universe

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 382
Author(s):  
V. V. Burdyuzha
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Large Scale ◽  
Cosmological Solution ◽  
Baryon Asymmetry ◽  
Composite Model ◽  
Quantum Process ◽  
Goldstone Bosons ◽  
The Universe ◽  
Relativistic Phase

The birth of the Universe, its dark components, and the next fundamental level of matter are briefly discussed. The classical cosmological solution for our Universe with a Λ-term has two branches divided by a gap. The quantum process of tunneling between branches took place. A model of a slowly swelling Universe in the result of the multiple reproductions of cosmological cycles arises naturally. The occurrence of baryon asymmetry is briefly discussed. The problem of the cosmological constant is solved and, thus, the crisis of physics connected with this constant is overcome. But we note that dark energy is evolving. Dark matter (part or all) consists of familon-type pseudo-Goldstone bosons with a mass of 10−5–10−3 eV. It follows the composite model of particles. This model reproduces three relativistic phase transitions in the medium of familons at different red shifts, forming a large scale structure of the Universe dark matter that was “repeated” by baryons. Here three generations of elementary particles are absolutely necessary.

scholarly journals Observational constraints of a new unified dark fluid and the H0 tension

2019 ◽  
Vol 490 (2) ◽  
pp. 2071-2085 ◽  
Author(s):  
Weiqiang Yang ◽  
Supriya Pan ◽  
Andronikos Paliathanasis ◽  
Subir Ghosh ◽  
Yabo Wu
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Early Time ◽  
Observational Constraints ◽  
Minimal Extension ◽  
Energy Evolution ◽  
The Universe ◽  
Different Sources

ABSTRACT Unified cosmological models have received a lot of attention in astrophysics community for explaining both the dark matter and dark energy evolution. The Chaplygin cosmologies, a well-known name in this group have been investigated matched with observations from different sources. Obviously, Chaplygin cosmologies have to obey restrictions in order to be consistent with the observational data. As a consequence, alternative unified models, differing from Chaplygin model, are of special interest. In the present work, we consider a specific example of such a unified cosmological model, that is quantified by only a single parameter μ, that can be considered as a minimal extension of the Λ-cold dark matter cosmology. We investigate its observational boundaries together with an analysis of the universe at large scale. Our study shows that at early time the model behaves like a dust, and as time evolves, it mimics a dark energy fluid depicting a clear transition from the early decelerating phase to the late cosmic accelerating phase. Finally, the model approaches the cosmological constant boundary in an asymptotic manner. We remark that for the present unified model, the estimations of H0 are slightly higher than its local estimation and thus alleviating the H0 tension.

scholarly journals RECONSTRUCTION OF 5D COSMOLOGICAL MODELS FROM RECENT OBSERVATIONS

2007 ◽  
Vol 16 (10) ◽  
pp. 1573-1579
Author(s):  
CHENGWU ZHANG ◽  
LIXIN XU ◽  
YONGLI PING ◽  
HONGYA LIU
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Cosmological Solution ◽  
Type Ia Supernovae ◽  
Shift Parameter ◽  
Type Ia ◽  
Ia Supernovae ◽  
Best Fit ◽  
The Universe

We use a parameterized equation of state (EOS) of dark energy to a 5D Ricci-flat cosmological solution and suppose the universe contains two major components: dark matter and dark energy. Using the recent observational datasets: the latest 182 type Ia Supernovae Gold data, the three-year WMAP CMB shift parameter and the SDSS baryon acoustic peak, we obtain the best fit values of the EOS and two major components' evolution. We find that the best fit EOS crosses -1 in the near past where z ≃ 0.07, the present best fit value of wx(0) < -1 and for this model, the universe experiences the acceleration at about z ≃ 0.5.

Observational and astrophysical cosmology: 1980–2018

2019 ◽  
pp. 375-423
Author(s):  
Malcolm S. Longair
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Constant ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Semiconductor Detectors ◽  
Empirical Knowledge ◽  
Global Geometry ◽  
The Universe ◽  
Large Scale Structure Formation

Since 1980, our empirical knowledge of the universe has advanced tremendously and precision cosmology has become a reality. These developments have been largely technology-driven, the result of increased computer power, new generations of telescopes for all wavebands, new types of semiconductor detectors, such as CCDs, and major investments by many nations in superb observing facilities. The discipline also benefitted from the influx of experimental and theoretical physicists into the cosmological arena. The accuracy and reliability of the values of the cosmological parameters has improved dramatically, many of them now being known to about 1%. The ΛCDM model provides a remarkable fit to all the observational data, demonstrating that the cosmological constant is non-zero and that the global geometry of the universe is flat. The underlying physics of galaxy and large-scale structure formation has advanced dramatically and demonstrated the key roles played by dark matter and dark energy.

Cosmology Today

Daedalus ◽  
2014 ◽  
Vol 143 (4) ◽  
pp. 125-133
Author(s):  
David N. Spergel
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Empty Space ◽  
Microwave Background ◽  
Astronomical Observations ◽  
Basic Parameters ◽  
Age Of The Universe ◽  
The Universe

We seem to live in a simple but strange universe. Our basic cosmological model fits a host of astronomical observations with only five basic parameters: the age of the universe, the density of atoms, the density of matter, the initial “lumpiness” of the universe, and a parameter that describes whether this lumpiness is more pronounced on smaller physical scales. Our observations of the cosmic microwave background fluctuations determine these parameters with uncertainties of only 1 to 2 percent. The same model also provides an excellent fit to the large-scale clustering of galaxies and gas, the properties of galaxy clusters, observations of gravitational lensing, and supernova-based measurements of the Hubble relation. This model implies that we live in a strange universe: atoms make up only 4 percent of the visible universe, dark matter makes up 24 percent, and dark energy – energy associated with empty space – makes up 72 percent.

scholarly journals THE TUNNELING, THE SECOND ORDER RELATIVISTIC PHASE TRANSITIONS AND PROBLEM OF THE MACROSCOPIC UNIVERSE ORIGIN

1996 ◽  
Vol 05 (03) ◽  
pp. 273-292 ◽  
Author(s):  
V.V. BURDYUZHA ◽  
Yu.N. PONOMAREV ◽  
O.D. LALAKULICH ◽  
G.M. VERESHKOV
Keyword(s):  
Cosmological Solution ◽  
Second Order ◽  
Quasi Equilibrium ◽  
Quantum Process ◽  
Gut Scale ◽  
Kinetics Of ◽  
The Universe ◽  
Quantum Geometrodynamics ◽  
Relativistic Phase ◽  
Number Of Particles

We propose that the Universe was created from “Nothing” with a relatively small number of particles and it very quick relaxed to a quasi-equilibrium state at the Planck parameters. The classic cosmological solution for this Universe, with the calculation of its ability to undergo the second order relativistic phase transition (RPT), has two branches divided by a gap. On one of these branches near to the “Nothing” state the second order RPT is not possible at the GUT scale. The other branch is thermodynamically unstable. The quantum process of tunneling between the cosmological solution branches and the kinetics of the second order RPT are investigated by numerical methods. Another quantum geometrodynamics process (bounce from singularity) is also taken into consideration. It is shown that the discussed phenomenon with the calculation of all RPTs from the GUT scale (1016 Gev) to the Salam-Weinberg scale (102 Gev) gives the new cosmological scenarios of the macroscopic Universe origin with the observable number of particles.

scholarly journals Cosmology with weak lensing surveys

2005 ◽  
Vol 363 (1837) ◽  
pp. 2675-2691 ◽  
Author(s):  
Dipak Munshi ◽  
Patrick Valageas
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Gravitational Lensing ◽  
Large Scale ◽  
High Redshift ◽  
Cosmological Parameters ◽  
Power Spectra ◽  
Weak Lensing ◽  
Satellite Mission ◽  
The Universe

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening mass. Since the lensing effects arise from deflections of the light rays due to fluctuations of the gravitational potential, they can be directly related to the underlying density field of the large-scale structures. Weak gravitational surveys are complementary to both galaxy surveys and cosmic microwave background observations as they probe unbiased nonlinear matter power spectra at medium redshift. Ongoing CMBR experiments such as WMAP and a future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period, ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g. SNAP) or the Large-aperture Synoptic Survey Telescope will play a major role in advancing our understanding of the universe in this direction. In this review article, we describe various aspects of probing the matter power spectrum and the bispectrum and other related statistics with weak lensing surveys. This can be used to probe the background dynamics of the universe as well as the nature of dark matter and dark energy.

Inflation, dark matter, and dark energy

2019 ◽  
pp. 423-464
Author(s):  
Malcolm S. Longair ◽  
Chris Smeenk
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Power Spectrum ◽  
Early Universe ◽  
Particle Physics ◽  
Large Scale ◽  
Initial State ◽  
Large Scale Structures ◽  
Initial Power ◽  
The Universe

The success of the ΛCDM model has raised a number of challenging problems for the origin of structure in the universe and the initial state from which it evolved. The origins of these basic cosmological problems are described. The dark matter must be non-baryonic, but its nature has not been established. Likewise, the nature of the dark energy is not understood. The inflationary model for the very early universe has had some undoubted successes in accounting for the initial power-spectrum of fluctuations from which large-scale structures formed but there is no physical realization of the inflaton field. Defects formed during phase transitions in the early universe cannot account for the initial power spectrum of fluctuations, but may have some part to play in structure formation. The origin of the baryon-antibaryon asymmetry in the early universe is not understood in terms of theories of particle physics.

scholarly journals FORMATION OF DARK MATTER HALOES IN A HOMOGENEOUS DARK ENERGY UNIVERSE

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1397-1403
Author(s):  
L. MARASSI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Large Scale ◽  
State Parameter ◽  
Mass Function ◽  
Accelerated Expansion ◽  
X Ray ◽  
Energy Models ◽  
Dark Energy Component ◽  
Standard Press

Several independent cosmological tests have shown evidences that the energy density of the universe is dominated by a dark energy component, which causes the present accelerated expansion. The large scale structure formation can be used to probe dark energy models, and the mass function of dark matter haloes is one of the best statistical tools to perform this study. We present here a statistical analysis of mass functions of galaxies under a homogeneous dark energy model, proposed in the work of Percival (2005), using an observational flux-limited X-ray cluster survey, and CMB data from WMAP. We compare, in our analysis, the standard Press–Schechter (PS) approach (where a Gaussian distribution is used to describe the primordial density fluctuation field of the mass function), and the PL (power–law) mass function (where we apply a non-extensive q-statistical distribution to the primordial density field). We conclude that the PS mass function cannot explain at the same time the X-ray and the CMB data (even at 99% confidence level), and the PS best fit dark energy equation of state parameter is ω = -0.58, which is distant from the cosmological constant case. The PL mass function provides better fits to the HIFLUGCS X-ray galaxy data and the CMB data; we also note that the ω parameter is very sensible to modifications in the PL free parameter, q, suggesting that the PL mass function could be a powerful tool to constrain dark energy models.

scholarly journals Dark Matter and the Baryon Asymmetry of the Universe

2006 ◽  
Vol 96 (4) ◽  
Author(s):  
Glennys R. Farrar ◽  
Gabrijela Zaharijas
Keyword(s):  
Dark Matter ◽  
Baryon Asymmetry ◽  
The Universe

scholarly journals INTERACTION BETWEEN DARK ENERGY AND DARK MATTER: OBSERVATIONAL CONSTRAINTS FROM OHD, BAO, CMB AND SNe Ia

2013 ◽  
Vol 22 (14) ◽  
pp. 1350082 ◽  
Author(s):  
SHUO CAO ◽  
NAN LIANG
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Observational Constraints ◽  
Coincidence Problem ◽  
Cosmological Constraints ◽  
Coincidence Index ◽  
Acceleration Of The Universe ◽  
Interaction Term ◽  
Negative Coupling ◽  
The Universe

In order to test if there is energy transfer between dark energy (DE) and dark matter (DM), we investigate cosmological constraints on two forms of nontrivial interaction between the DM sector and the sector responsible for the acceleration of the universe, in light of the newly revised observations including OHD, CMB, BAO and SNe Ia. More precisely, we find the same tendencies for both phenomenological forms of the interaction term Q = 3γHρ, i.e. the parameter γ to be a small number, |γ| ≈ 10-2. However, concerning the sign of the interaction parameter, we observe that γ > 0 when the interaction between dark sectors is proportional to the energy density of dust matter, whereas the negative coupling (γ < 0) is preferred by observations when the interaction term is proportional to DE density. We further discuss two possible explanations to this incompatibility and apply a quantitative criteria to judge the severity of the coincidence problem. Results suggest that the γm IDE model with a positive coupling may alleviate the coincidence problem, since its coincidence index C is smaller than that for the γd IDE model, the interacting quintessence and phantom models by four orders of magnitude.

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