scholarly journals DARK MATTER PREDICTION FROM CANONICAL QUANTUM GRAVITY WITH FRAME FIXING

2004 ◽  
Vol 19 (37) ◽  
pp. 2777-2784 ◽  
Author(s):  
GIOVANNI CORVINO ◽  
GIOVANNI MONTANI
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Dark Matter Candidate ◽  
New Energy ◽  
Frw Model ◽  
Canonical Quantum Gravity ◽  
The Universe ◽  
Matter Component ◽  
Canonical Quantum ◽  
Relativistic Matter

We show how, in canonical quantum cosmology, the frame fixing induces a new energy density contribution having features compatible with the (actual) cold dark matter component of the Universe. First we quantize the closed Friedmann–Robertson–Walker (FRW) model in a synchronous reference and determine the spectrum of the super-Hamiltonian in the presence of ultra-relativistic matter and a perfect gas contribution. Then we include in this model small inhomogeneous (spherical) perturbations in the spirit of the Lemaitre–Tolman cosmology. The main issue of our analysis consists in outlining that, in the classical limit, the nonzero eigenvalue of the super-Hamiltonian can account for the present value of the dark matter critical parameter. Furthermore we obtain a direct correlation between the inhomogeneities in our dark matter candidate and those that appear in the ultra-relativistic matter.

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 N-body Simulations of Galaxy Formation

1988 ◽  
Vol 130 ◽  
pp. 259-271
Author(s):  
Carlos S. Frenk
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Large Scale Structure ◽  
High Density ◽  
Galactic Halos ◽  
Body Techniques ◽  
Massive Halos ◽  
The Universe

Modern N-body techniques allow the study of galaxy formation in the wider context of the formation of large-scale structure in the Universe. The results of such a study within the cold dark matter cosmogony are described. Dark galactic halos form at relatively recent epochs. Their properties and abundance are similar to those inferred for the halos of real galaxies. Massive halos tend to form preferentially in high density regions and as a result the galaxies that form within them are significantly more clustered than the underlying mass. This natural bias may be strong enough to reconcile the observed clustering of galaxies with the assumption that Ω = 1.

ARITHMETIC QUANTUM GRAVITY

2010 ◽  
Vol 19 (14) ◽  
pp. 2305-2310 ◽  
Author(s):  
AXEL KLEINSCHMIDT ◽  
HERMANN NICOLAI
Keyword(s):  
Quantum Gravity ◽  
Algebraic Structure ◽  
Complete Resolution ◽  
Quantum Level ◽  
Cosmological Singularity ◽  
Quantum Billiard ◽  
Symmetry Structure ◽  
Canonical Quantum Gravity ◽  
The Universe ◽  
Canonical Quantum

The arithmetic chaos of classical (super)gravity near a spacelike singularity is elevated to the quantum level via the construction of a cosmological quantum billiard system. Its precise formulation, together with its underlying algebraic structure, allows for a general analysis of the wavefunction of the universe near the singularity. We argue that the extension of these results beyond the billiard approximation may provide a concrete mechanism for emergent space as well as new perspectives on several long-standing issues in canonical quantum gravity. The exponentially growing complexity of the underlying symmetry structure could introduce an element of non-computability that effectively "screens" the cosmological singularity from a complete resolution.

scholarly journals DARK MATTER AXIONS

2010 ◽  
Vol 25 (02n03) ◽  
pp. 554-563 ◽  
Author(s):  
P. SIKIVIE
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Cold Dark Matter ◽  
Einstein Condensate ◽  
Dark Matter Halos ◽  
Linear Regime ◽  
Bose Einstein Condensate ◽  
Invisible Axion ◽  
Bose Einstein ◽  
The Universe

The hypothesis of an 'invisible' axion was made by Misha Shifman and others, approximately thirty years ago. It has turned out to be an unusually fruitful idea, crossing boundaries between particle physics, astrophysics and cosmology. An axion with mass of order 10-5 eV (with large uncertainties) is one of the leading candidates for the dark matter of the universe. It was found recently that dark matter axions thermalize and form a Bose-Einstein condensate (BEC). Because they form a BEC, axions differ from ordinary cold dark matter (CDM) in the non-linear regime of structure formation and upon entering the horizon. Axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microwave anisotropy multipoles. Because there is evidence for these phenomena, unexplained with ordinary CDM, an argument can be made that the dark matter is axions.

Statefinder diagnostic for exponential harmonic field

2020 ◽  
Vol 35 (26) ◽  
pp. 2050161
Author(s):  
A. D. Kanfon ◽  
F. Mavoa ◽  
G. Koto N’Gobi
Keyword(s):  
Dark Matter ◽  
Numerical Analysis ◽  
Cold Dark Matter ◽  
Specific Method ◽  
Statefinder Parameters ◽  
Harmonic Field ◽  
Cold Dark Matter Model ◽  
Matter Model ◽  
The Universe ◽  
Dark Matter Model

The dynamic study of the harmonic exponential field has been made using the statefinder diagnostic. By the use of a specific method, we find out the statefinder parameters [Formula: see text], [Formula: see text] according to the deceleration parameter and the redshift. The numerical analysis of these parameters brings out the transition between the accelerated and decelerated phases of the universe. There is also an attracting effect from the SCDM (Standard Cold Dark Matter) model toward the LCDM model ([Formula: see text]CDM). In view of the results this study allows us to classify the exponential harmonic field among the quintessential models.

scholarly journals N-Body Results on Dark Matter

1987 ◽  
Vol 117 ◽  
pp. 263-278
Author(s):  
Simon D. M. White
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Cold Dark Matter ◽  
Density Fluctuations ◽  
Major Difficulty ◽  
Mass Distributions ◽  
Galaxy Distribution ◽  
Galaxy Halos ◽  
Flat Rotation Curves ◽  
The Universe

The structure of the dominant “dark” component of the Universe may evolve primarily under the influence of gravity. A number of models for the evolution of the Universe make specific predictions for the statistical properties of density fluctuations at early times. N-body simulations can follow the nonlinear development of such fluctuations to the present day. A major difficulty arises because we cannot observe the present mass distribution directly. Recent N-body work has concentrated on models dominated by weakly interacting free elementary particles. Neutrino-dominated but otherwise conventional cosmologies pass rapidly from a smooth distribution to one dominated by lumps with masses greater than those of any known object. Cosmologies dominated by “cold dark matter” produce mass distributions which fit the observed galaxy distribution (i) if Ω = 0.1–0.2 and galaxies follow the mass distribution, or (ii) if Ω = 1, HO< 50 km/s/Mpc and galaxies form preferentially in high density regions. In the latter case, clumps form with flat rotation curves with about the amplitude and abundance expected for galaxy halos.

A classical non-quantum all-time time-symmetrical zero-energy single-bounce model for the creation, big bang, and death of the universe

2019 ◽  
Vol 28 (14) ◽  
pp. 1944024 ◽  
Author(s):  
Arthur E. Fischer
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Big Bang ◽  
Final States ◽  
Level Curve ◽  
Zero Energy ◽  
Time Model ◽  
Gravitational Effects ◽  
The Big Bang ◽  
The Universe

In this paper, we show how the [Formula: see text]CDM (Lambda Cold Dark Matter) Standard Model for cosmology can be extrapolated backwards through the big bang into the infinite past to yield an all-time model of the universe with scale factor given by [Formula: see text] defined and continuous for all [Formula: see text] and smooth ([Formula: see text] and satisfying Friedmann’s equation for all [Formula: see text]. At the big bang [Formula: see text], there is a nondifferentiable cusp singularity and our model shows some details of the behavior of the universe at this singularity. Our model is a zero-energy single-bounce model and an examination of the [Formula: see text]-plot of the [Formula: see text] level curve gives critical information about the initial and final states of the universe, about the evolution of the universe, and about the behavior of the universe at the big bang. Our results show that much can be said classically about the birth, big bang and death of the universe before one needs to reach for quantum gravitational effects.

Pilgrim dark energy models in fractal universe

2016 ◽  
Vol 26 (06) ◽  
pp. 1750049 ◽  
Author(s):  
Abdul Jawad ◽  
Shamaila Rani ◽  
Ines G. Salako ◽  
Faiza Gulshan
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
Accelerated Expansion ◽  
Freezing And Thawing ◽  
Eos Parameter ◽  
Pilgrim Dark Energy ◽  
Energy Models ◽  
Expansion Behavior ◽  
The Universe

We discuss the cosmological implications of interacting pilgrim dark energy (PDE) models (with Hubble, Granda–Oliveros and generalized ghost cutoffs) with cold dark matter ([Formula: see text]CDM) in fractal cosmology by assuming the flat universe. We observe that the Hubble parameter lies within observational suggested ranges while deceleration parameter represents the accelerated expansion behavior of the universe. The equation of state (EoS) parameter ([Formula: see text]) corresponds to the quintessence region and phantom region for different cases of [Formula: see text]. Further, we can see that [Formula: see text]–[Formula: see text] (where prime indicates the derivative with respect to natural logarithmic of scale factor) plane describes the freezing and thawing regions and also corresponds to [Formula: see text] limit for some cases of [Formula: see text] (PDE parameter). It is also noted that the [Formula: see text]–[Formula: see text] (state-finder parameters) plane corresponds to [Formula: see text] limit and also shows the Chaplygin as well as phantom/quintessence behavior. It is observed that pilgrim dark energy models in fractal cosmology expressed the consistent behavior with recent observational schemes.

scholarly journals THE HIGGS PORTAL AND AN UNIFIED MODEL FOR DARK ENERGY AND DARK MATTER

2008 ◽  
Vol 23 (30) ◽  
pp. 4817-4827 ◽  
Author(s):  
O. BERTOLAMI ◽  
R. ROSENFELD
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Higgs Boson ◽  
Higgs Field ◽  
Vacuum Expectation ◽  
Classical Field ◽  
Dark Matter Candidate ◽  
Hidden Sector ◽  
Quintessence Field ◽  
The Universe

We examine a scenario where the Higgs boson is coupled to an additional Standard Model singlet scalar field from a hidden sector. We show that, in the case where this field is very light and has already relaxed to its nonzero vacuum expectation value, one gets a very stringent limit on the mixing angle between the hidden sector scalar and the Higgs field from fifth force experiments. However, this limit does not imply in a small coupling due to the large difference of vacuum expectation values. In the case that the hidden sector scalar is identified with the quintessence field, responsible for the recent acceleration of the universe, the most natural potential describing the interaction is disfavored since it results in a time-variation of the Fermi scale. We show that an ad hoc modification of the potential describing the Higgs interaction with the quintessence field may result in an unified picture of dark matter and dark energy, where dark energy is the zero-mode classical field rolling the usual quintessence potential and the dark matter candidate is the quantum excitation (particle) of the field, which is produced in the universe due to its coupling to the Higgs boson. This coupling also generates a mass for the new particle that, contrary to usual quintessence models, does not have to be small, since it does not affect the evolution of classical field. In this scenario, a feasible dark matter density can be, under conditions, obtained.

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