scholarly journals SUPERHEAVY PARTICLES IN FRIEDMANN COSMOLOGY AND THE DARK MATTER PROBLEM

2002 ◽  
Vol 11 (03) ◽  
pp. 433-436 ◽  
Author(s):  
A. A. GRIB ◽  
YU. V. PAVLOV
Keyword(s):  
Dark Matter ◽  
Gravitational Field ◽  
Early Universe ◽  
Particle Creation ◽  
Baryon Number ◽  
Matter Density ◽  
Friedmann Model ◽  
Dark Matter Density ◽  
The Universe

The model of creation of observable particles and particles of the dark matter, considered to be superheavy particles, due to particle creation by the gravitational field of the Friedmann model of the early Universe is given. Estimates on the parameters of the model leading to observable values of the baryon number of the Universe and the dark matter density are made.

scholarly journals Dark matter density profile and galactic metric in Eddington-inspired Born–Infeld gravity

2014 ◽  
Vol 29 (09) ◽  
pp. 1450049 ◽  
Author(s):  
Tiberiu Harko ◽  
Francisco S. N. Lobo ◽  
M. K. Mak ◽  
Sergey V. Sushkov
Keyword(s):  
Dark Matter ◽  
Gravitational Field ◽  
Density Profile ◽  
Galactic Center ◽  
Matter Density ◽  
Dark Matter Halos ◽  
Field Equations ◽  
Metric Tensor ◽  
Dark Matter Density ◽  
Gravitational Field Equations

We consider the density profile of pressureless dark matter in Eddington-inspired Born–Infeld (EiBI) gravity. The gravitational field equations are investigated for a spherically symmetric dark matter galactic halo, by adopting a phenomenological tangential velocity profile for test particles moving in stable circular orbits around the galactic center. The density profile and the mass distribution, as well as the general form of the metric tensor is obtained by numerically integrating the gravitational field equations, and in an approximate analytical form by using the Newtonian limit of the theory. In the weak field limit, the dark matter density distribution is described by the Lane–Emden equation with polytropic index n = 1, and is nonsingular at the galactic center. The parameter κ of the theory is determined so that the theory could provide a realistic description of the dark matter halos. The gravitational properties of the dark matter halos are also briefly discussed in the Newtonian approximation.

Uniform dark matter density model of the Universe

2009 ◽  
Vol 22 (3) ◽  
pp. 325-333 ◽  
Author(s):  
Jaroslav Hynecek
Keyword(s):  
Dark Matter ◽  
Matter Density ◽  
Density Model ◽  
Dark Matter Density ◽  
The Universe

scholarly journals Possible Effects of Non-Vanishing Particle Sizes in the Early Universe

1997 ◽  
Vol 12 (38) ◽  
pp. 2927-2931 ◽  
Author(s):  
Hidezumi Terazawa
Keyword(s):  
Early Universe ◽  
Quark Gluon Plasma ◽  
Baryon Number ◽  
Gluon Plasma ◽  
Effective Radius ◽  
Inflationary Universe ◽  
Particle Sizes ◽  
Friedmann Model ◽  
Quark Number ◽  
The Universe

Possible effects of the non-vanishing sizes of particles (atoms, nuclei, nucleons, quarks, and leptons) in the early universe (the temperature T) are discussed in an extended Friedmann model of the universe (the scale a). In particular we point out the following possibilities: (a) if rq>(2NB/π)-1/3a, most of the proposed scenarios for T>103 TeV including the inflationary universe are unrealistic, (b) rq<(2NB/π)-1/3a due to the smallness of rq(≲ 10-27 cm ), (c) rq<(2NB/π)-1/3a due to the smallness of NB in which the baryon number (or quark number) must be generated at T≲03 TeV if rq≳ 10-17 cm (where rq and NB are the effective radius of quarks and the baryon number in the universe, respectively), and (d) for T≳ 103 TeV , the universe was filled not with quark–gluon plasma but with "subquark plasma".

scholarly journals The Evaporation of Strange Matter in the Early Universe

1987 ◽  
Vol 117 ◽  
pp. 489-489
Author(s):  
Charles Alcock ◽  
Edward Farhi
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Lower Energy ◽  
Baryon Number ◽  
Strange Matter ◽  
Strange Quarks ◽  
The Earth ◽  
The Universe ◽  
Quark Phase

A new candidate for the dark matter of the universe is strange matter. This substance consists of roughly equal numbers of up, down and strange quarks confined in a quark phase which is conjectured to have a lower energy per baryon number than ordinary nuclei. Strange matter is absolutely stable, has a density comparable to that of nuclei and can exist in lumps ranging in size from a few fermis to ∼ 10 km. If it is distributed in space in lumps larger than ∼ 1 cm, it could close the universe without ever encountering the earth and would be astronomically unobservable.

scholarly journals Displaced new physics at colliders and the early universe before its first second

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Lorenzo Calibbi ◽  
Francesco D’Eramo ◽  
Sam Junius ◽  
Laura Lopez-Honorez ◽  
Alberto Mariotti
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Upper Bound ◽  
New Physics ◽  
Early History ◽  
Relic Density ◽  
History Of ◽  
Indirect Information ◽  
The Universe

Abstract Displaced vertices at colliders, arising from the production and decay of long-lived particles, probe dark matter candidates produced via freeze-in. If one assumes a standard cosmological history, these decays happen inside the detector only if the dark matter is very light because of the relic density constraint. Here, we argue how displaced events could very well point to freeze-in within a non-standard early universe history. Focusing on the cosmology of inflationary reheating, we explore the interplay between the reheating temperature and collider signatures for minimal freeze-in scenarios. Observing displaced events at the LHC would allow to set an upper bound on the reheating temperature and, in general, to gather indirect information on the early history of the universe.

scholarly journals Determining the local dark matter density with LAMOST data

2016 ◽  
Vol 458 (4) ◽  
pp. 3839-3850 ◽  
Author(s):  
Qiran Xia ◽  
Chao Liu ◽  
Shude Mao ◽  
Yingyi Song ◽  
Lan Zhang ◽  
...  
Keyword(s):  
Dark Matter ◽  
Matter Density ◽  
Dark Matter Density

scholarly journals Isolated dwarf galaxies: from cuspy to flat dark matter density profiles and metalicity gradients

2010 ◽  
Vol 514 ◽  
pp. A47 ◽  
Author(s):  
S. Pasetto ◽  
E. K. Grebel ◽  
P. Berczik ◽  
R. Spurzem ◽  
W. Dehnen
Keyword(s):  
Dark Matter ◽  
Dwarf Galaxies ◽  
Matter Density ◽  
Density Profiles ◽  
Dark Matter Density

scholarly journals Non-Gaussian inference from non-linear and non-Poisson biased distributed data

2014 ◽  
Vol 10 (S306) ◽  
pp. 258-261
Author(s):  
Metin Ata ◽  
Francisco-Shu Kitaura ◽  
Volker Müller
Keyword(s):  
Dark Matter ◽  
Statistical Inference ◽  
Computer Code ◽  
Matter Density ◽  
Density Field ◽  
Distributed Data ◽  
Dark Matter Density ◽  
Posterior Sampling ◽  
Non Linear ◽  
Non Gaussian

AbstractWe study the statistical inference of the cosmological dark matter density field from non-Gaussian, non-linear and non-Poisson biased distributed tracers. We have implemented a Bayesian posterior sampling computer-code solving this problem and tested it with mock data based onN-body simulations.

scholarly journals Foundations of a Theory of Gravity with a Constraint and Its Canonical Quantization

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Alexander P. Sobolev
Keyword(s):  
General Relativity ◽  
Gravitational Field ◽  
Early Universe ◽  
Canonical Quantization ◽  
Entropy Density ◽  
Maximum Temperature ◽  
Past Century ◽  
Physical Point ◽  
Theory Of Gravity ◽  
The Universe

AbstractThe gravitational equations were derived in general relativity (GR) using the assumption of their covariance relative to arbitrary transformations of coordinates. It has been repeatedly expressed an opinion over the past century that such equality of all coordinate systems may not correspond to reality. Nevertheless, no actual verification of the necessity of this assumption has been made to date. The paper proposes a theory of gravity with a constraint, the degenerate variants of which are general relativity (GR) and the unimodular theory of gravity. This constraint is interpreted from a physical point of view as a sufficient condition for the adiabaticity of the process of the evolution of the space–time metric. The original equations of the theory of gravity with the constraint are formulated. On this basis, a unified model of the evolution of the modern, early, and very early Universe is constructed that is consistent with the observational astronomical data but does not require the hypotheses of the existence of dark energy, dark matter or inflatons. It is claimed that: physical time is anisotropic, the gravitational field is the main source of energy of the Universe, the maximum global energy density in the Universe was 64 orders of magnitude smaller the Planckian one, and the entropy density is 18 orders of magnitude higher the value predicted by GR. The value of the relative density of neutrinos at the present time and the maximum temperature of matter in the early Universe are calculated. The wave equation of the gravitational field is formulated, its solution is found, and the nonstationary wave function of the very early Universe is constructed. It is shown that the birth of the Universe was random.

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