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 Large-Scale Structure in the Universe: Spatial Distribution and Peculiar Velocities

1987 ◽  
Vol 124 ◽  
pp. 335-348
Author(s):  
Neta A. Bahcall
Keyword(s):  
Dark Matter ◽  
Spatial Distribution ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Clusters Of Galaxies ◽  
Large Scale Structures ◽  
Peculiar Velocities ◽  
Scale Structures ◽  
The Universe

The evidence for the existence of very large scale structures, ∼ 100h−1Mpc in size, as derived from the spatial distribution of clusters of galaxies is summarized. Detection of a ∼ 2000 kms−1 elongation in the redshift direction in the distribution of the clusters is also described. Possible causes of the effect are peculiar velocities of clusters on scales of 10–100h−1Mpc and geometrical elongation of superclusters. If the effect is entirely due to the peculiar velocities of clusters, then superclusters have masses of order 1016.5M⊙ and may contain a larger amount of dark matter than previously anticipated.

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 ACCELERATION AND DECELERATION IN THE CURVATURE-INDUCED PHANTOM MODEL OF THE LATE AND FUTURE UNIVERSE: COSMIC COLLAPSE AND ITS QUANTUM ESCAPE

2009 ◽  
Vol 18 (05) ◽  
pp. 865-887
Author(s):  
S. K. SRIVASTAVA ◽  
J. DUTTA
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Quantum Gravity ◽  
Cosmological Constant ◽  
Early Universe ◽  
High Energy ◽  
High Energy Density ◽  
Energy Models ◽  
Acceleration And Deceleration ◽  
The Universe

In this paper, the cosmology of the late and future universe is obtained from f(R) gravity with nonlinear curvature terms R2 and R3 (R is the Ricci scalar curvature). It is different from f(R) dark energy models where nonlinear curvature terms are taken as a gravitational alternative to dark energy. In the present model, neither linear nor nonlinear curvature terms are taken as dark energy. Rather, dark energy terms are induced by curvature terms and appear in the Friedmann equation derived from f(R) gravitational equations. This approach has an advantage over f(R) dark energy models in three ways: (i) results are consistent with WMAP observations, (ii) dark matter is produced from the gravitational sector and (iii) the universe expands as ~ t2/3 during dominance of the curvature-induced dark matter, which is consistent with the standard cosmology. Curvature-induced dark energy mimics phantom and causes late acceleration. It is found that transition from matter-driven deceleration to acceleration takes place at the redshift 0.36 at time 0.59 t0 (t0 is the present age of the universe). Different phases of this model, including acceleration and deceleration during the phantom phase, are investigated. It is found that expansion of the universe will stop at the age of 3.87 t0 + 694.4 kyr. After this epoch, the universe will contract and collapse by the time of 336.87 t0 + 694.4 kyr. Further, it is shown that cosmic collapse obtained from classical mechanics can be avoided by making quantum gravity corrections relevant near the collapse time due to extremely high energy density and large curvature analogous to the state of the very early universe. Interestingly, the cosmological constant is also induced here; it is extremely small in the classical domain but becomes very high in the quantum domain. This result explains the largeness of the cosmological constant in the early universe due to quantum gravity effects during this era and its very low value in the present universe due to negligible quantum effect in the late universe.

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.

scholarly journals Gravitino Warm Dark Matter Motivated by Gauge-Mediated Supersymmetry Breaking Theories

1997 ◽  
Vol 12 (17) ◽  
pp. 1275-1282 ◽  
Author(s):  
M. Kawasaki ◽  
Naoshi Sugiyama ◽  
T. Yanagida
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Supersymmetry Breaking ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Baryon Density ◽  
Present Observation ◽  
Matter Model ◽  
The Universe ◽  
Dark Matter Model

Gauge-mediated supersymmetry breaking models suggest the presence of the light gravitino with mass ~ 1 keV which can be warm dark matter in our universe. We consider large scale structure of the universe in the warm dark matter model and find that the power spectrum of the gravitino dark matter is almost the same as that of a cold dark matter at scales larger than about 1 Mpc. We also study the Ly α absorption systems which are presumed to be galaxies at high redshifts and show that the baryon density in the damped Ly α absorption systems predicted by the gravitino dark matter model is quite consistent with the present observation.

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 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 Anisotropies in Luminosity Distance

1999 ◽  
Vol 183 ◽  
pp. 269-269
Author(s):  
Norimasa Sugiura ◽  
Naoshi Sugiyama ◽  
Misao Sasaki
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Linear Perturbation ◽  
Luminosity Distance ◽  
Raychaudhuri Equation ◽  
Density Perturbations ◽  
Frw Models ◽  
The Universe

Anisotropies in luminosity distance-redshift relation (dL − z relation) caused by the large-scale structure (LSS) of the universe are studied. We solve the Raychaudhuri equation on FRW models taking account of LSS by the linear perturbation method. Numerical calculations to evaluate the amplitude of the anisotropies are done on flat models with cosmological constant and open models, employing Cold Dark Matter models and COBE-normalization for the power spectrum of the density perturbations.

scholarly journals Dark Matter and Dark Energy in the Universe

2018 ◽  
Vol 14 (1) ◽  
pp. 5292-5295
Author(s):  
Yuanjie Li ◽  
Lihong Zhang ◽  
Peng Dong
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Dark Energy ◽  
Early Universe ◽  
Left Behind ◽  
Time Quantum ◽  
The Universe

This paper points out that not only all quantum-ghost puzzles occur in the Time Quantum Worm Hole, but also the dark matter in the universe is hidden in it. Dark energy is the contribution of the Planck black hole left behind by the early universe.

scholarly journals Primordial Perturbations, Early Evolution and Dark Matter in the Universe

1990 ◽  
Vol 43 (2) ◽  
pp. 123
Author(s):  
VN Lukash
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Large Scale ◽  
Transfer Functions ◽  
Interacting Particles ◽  
Cosmological Expansion ◽  
Classical Gravity ◽  
Further Development ◽  
Weakly Interacting Particles ◽  
The Universe

The problem of primordial cosmological perturbations which gave birth to the large scale structure of the universe is analysed from the time of their origin up to the nonlinear formation of the structure. We show how classical gravity accounts for the generation of perturbations near the beginning of the cosmological expansion. Dark matter which governs the further development of perturbations in the early universe includes both heavy and light weakly interacting particles. Transfer functions of the adiabatic and isothermal modes of perturbations are investigated and some astrophysical applications are given.

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