Real scalar field solutions of the EKG equations including matter

2020 ◽  
pp. 2150009
Author(s):  
A. Cabo Montes de Oca ◽  
D. Suarez Fontanella
Keyword(s):  
Dark Matter ◽  
Gravitational Field ◽  
Scalar Field ◽  
Scalar Fields ◽  
Stationary Solutions ◽  
Field Interaction ◽  
Small Bodies ◽  
Real Scalar ◽  
Static Solutions ◽  
Klein Gordon

Static (not stationary) solutions of the Einstein–Klein–Gordon (EKG) equations including matter are obtained for real scalar fields. The scalar field interaction with matter is considered. The introduced coupling allows the existence of static solutions in contraposition with the case of the simpler EKG equations for real scalar fields and gravity. Surprisingly, when the considered matter is a photon-like gas, it turns out that the gravitational field intensity at large radial distances becomes nearly a constant, exerting an approximately fixed force to small bodies at any distance. The effect is clearly related with the massless character of the photon-like field. It is also argued that the gravitational field can generate a bounding attraction, that could avoid the unlimited increase in mass with the radius of the obtained here solution. This phenomenon, if verified, may furnish a possible mechanism for explaining how the increasing gravitational potential associated to dark matter, finally decays at large distances from the galaxies. A method for evaluating these photon bounding effects is just formulated in order to be further investigated.

scholarly journals FERMIONIC AND SCALAR FIELDS AS SOURCES OF INTERACTING DARK MATTER–DARK ENERGY

2011 ◽  
Vol 20 (13) ◽  
pp. 2543-2558 ◽  
Author(s):  
SAMUEL LEPE ◽  
JAVIER LORCA ◽  
FRANCISCO PEÑA ◽  
YERKO VÁSQUEZ
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Analytical Solution ◽  
Scalar Fields ◽  
Nonminimal Coupling ◽  
Field Equations ◽  
Fermionic Field ◽  
Minimal Coupling ◽  
Constant Type

From a variational action with nonminimal coupling with a scalar field and classical scalar and fermionic interaction, cosmological field equations can be obtained. Imposing a Friedmann–Lemaître–Robertson–Walker (FLRW) metric, the equations lead directly to a cosmological model consisting of two interacting fluids, where the scalar field fluid is interpreted as dark energy and the fermionic field fluid is interpreted as dark matter. Several cases were studied analytically and numerically. An important feature of the non-minimal coupling is that it allows crossing the barrier from a quintessence to phantom behavior. The insensitivity of the solutions to one of the parameters of the model permits it to find an almost analytical solution for the cosmological constant type of universe.

Black hole in balance with dark matter

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040050
Author(s):  
Boris E. Meierovich
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Phase Equilibrium ◽  
Vector Field ◽  
Scalar Field ◽  
Total Mass ◽  
Metric Tensor ◽  
Static Solutions ◽  
Tensor Formula ◽  
Galaxy Rotation Curves

Equilibrium of a gravitating scalar field inside a black hole compressed to the state of a boson matter, in balance with a longitudinal vector field (dark matter) from outside is considered. Analytical consideration, confirmed numerically, shows that there exist static solutions of Einstein’s equations with arbitrary high total mass of a black hole, where the component of the metric tensor [Formula: see text] changes its sign twice. The balance of the energy-momentum tensors of the scalar field and the longitudinal vector field at the interface ensures the equilibrium of these phases. Considering a gravitating scalar field as an example, the internal structure of a black hole is revealed. Its phase equilibrium with the longitudinal vector field, describing dark matter on the periphery of a galaxy, determines the dependence of the velocity on the plateau of galaxy rotation curves on the mass of a black hole, located in the center of a galaxy.

scholarly journals Could galactic magnetic fields be generated by charged ultra-light boson dark matter?

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Maribel Hernández ◽  
Ana A. Avilez ◽  
Tonatiuh Matos
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Magnetic Fields ◽  
Density Profile ◽  
Dark Matter Halo ◽  
Error Estimator ◽  
Rotation Curves ◽  
Complex Scalar ◽  
Virtual Photons ◽  
Klein Gordon

Abstract We study the possibility that large-scale magnetic fields observed in galaxies could be produced by a dark matter halo made of charged ultra-light bosons, that arise as excitations of a complex scalar field described by the Klein–Gordon equation with local U(1) symmetry which introduces electromagnetic fields that minimally couple to the complex scalar current and act as dark virtual photons. These virtual photons have an unknown coupling constant with real virtual photons. We constrain the final interaction using the observed magnetic fields in galaxies. We use classical solutions of the Klein–Gordon–Maxwell system to describe the density profile of dark matter and magnetic fields in galaxies. We consider two cases assuming spherical and dipolar spatial symmetries. For the LSB spherical galaxy F563-V2, we test the sensitivity of the predicted rotation curves in the charged Scalar Field Dark Matter (cSFDM) model to variations of the electromagnetic coupling and using the Fisher matrix error estimator, we set a constraint over that coupling by requiring that theoretical rotation curves lay inside the $$1\sigma $$1σ confidence region of observational data. We find that cSFDM haloes generate magnetic fields of the order of $$\mu G$$μG and reproduce the observed rotation curves of F563-V2 if the ultra-light boson has a charge $$\sim <10^{-13}e$$∼<10-13e for the monopole-like density profile and $$\sim <10^{-14}e$$∼<10-14e for the dipole-like one.

scholarly journals THE QUANTUM THEORY OF SCALAR FIELDS ON THE DE SITTER EXPANDING UNIVERSE

2008 ◽  
Vol 23 (16n17) ◽  
pp. 2563-2577 ◽  
Author(s):  
ION I. COTĂESCU ◽  
COSMIN CRUCEAN ◽  
ADRIAN POP
Keyword(s):  
Scalar Field ◽  
Gordon Equation ◽  
Scalar Fields ◽  
Wave Functions ◽  
De Sitter ◽  
Scalar Quantum ◽  
Long Time ◽  
Klein Gordon ◽  
Free Scalar ◽  
Special Time

New quantum modes of the free scalar field are derived in a special time-evolution picture that may be introduced in moving charts of de Sitter backgrounds. The wave functions of these new modes are solutions of the Klein–Gordon equation and energy eigenfunctions, defining the energy basis. This completes the scalar quantum mechanics where the momentum basis is well known for long time. In this enlarged framework the quantization of the scalar field can be done in canonical way obtaining the principal conserved one-particle operators and the Green functions.

scholarly journals ON THE TRANSITION FROM COMPLEX TO REAL SCALAR FIELDS IN MODERN COSMOLOGY

2011 ◽  
Vol 08 (08) ◽  
pp. 1815-1832 ◽  
Author(s):  
GIAMPIERO ESPOSITO ◽  
RAJU ROYCHOWDHURY ◽  
CLAUDIO RUBANO ◽  
PAOLO SCUDELLARO
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Scalar Fields ◽  
Complex Nature ◽  
Complex Scalar ◽  
Real Scalar ◽  
Symmetry Approach ◽  
Modern Cosmology ◽  
Complex Scalar Field ◽  
The Universe

We study some problems arising from the introduction of a complex scalar field in cosmology, modeling its possible behaviors in both the inflationary and dark energy stages of the universe. Such examples contribute to show that, while the complex nature of the scalar field can be indeed important during inflation, it loses its meaning in the later dark-energy dominated era of cosmology, when the phase of the complex field is practically constant, and there is indeed a transition from complex to real scalar field. In our considerations, the Noether symmetry approach turns out to be a useful tool once again. We arrive eventually at a potential containing the sixth and fourth powers of the scalar field, and the resulting semiclassical quantum cosmology is studied to gain a better understanding of the inflationary stage.

scholarly journals ABOUT BLACK HOLES WITH NONTRAPPING INTERIOR

1999 ◽  
Vol 14 (13) ◽  
pp. 2013-2022 ◽  
Author(s):  
ALEJANDRO CABO ◽  
ELOY AYÓN
Keyword(s):  
Scalar Field ◽  
Scalar Fields ◽  
Generalized Functions ◽  
Interior Solution ◽  
Schwarzschild Solution ◽  
Exterior Region ◽  
Trapped Surfaces ◽  
Proper Mass ◽  
Klein Gordon ◽  
Black Hole Solutions

Physical arguments related with the existence of black hole solutions having a non-trapping interior are discussed. Massive scalar fields interacting with gravity are considered. Interior asymptotic solutions showing a scalar field approaching a constant value at the horizon are given. It is argued that the coupled Einstein–Klein–Gordon equations can be satisfied in the sense of the generalized functions after removing a particular regularization designed for matching the interior solution with an external Schwarzschild space–time. The scalar field appears as just avoiding the appearance of closed trapped surfaces while coming from the exterior region. It also follows that the usual space integral over [Formula: see text] in the internal region just gives the total proper mass associated to the external Schwarzschild solution, as it should be expected.

scholarly journals Beyond Schrödinger-Poisson: nonrelativistic effective field theory for scalar dark matter

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Borna Salehian ◽  
Hong-Yi Zhang ◽  
Mustafa A. Amin ◽  
David I. Kaiser ◽  
Mohammad Hossein Namjoo
Keyword(s):  
Dark Matter ◽  
Scalar Fields ◽  
Effective Field ◽  
Leading Order ◽  
Relativistic Corrections ◽  
Cosmological Context ◽  
Relativistic Regime ◽  
Klein Gordon ◽  
Relationship Of ◽  
Insight Into

Abstract Massive scalar fields provide excellent dark matter candidates, whose dynamics are often explored analytically and numerically using nonrelativistic Schrödinger-Poisson (SP) equations in a cosmological context. In this paper, starting from the nonlinear and fully relativistic Klein-Gordon-Einstein (KGE) equations in an expanding universe, we provide a systematic framework for deriving the SP equations, as well as relativistic corrections to them, by integrating out ‘fast modes’ and including nonlinear metric and matter contributions. We provide explicit equations for the leading-order relativistic corrections, which provide insight into deviations from the SP equations as the system approaches the relativistic regime. Upon including the leading-order corrections, our equations are applicable beyond the domain of validity of the SP system, and are simpler to use than the full KGE case in some contexts. As a concrete application, we calculate the mass-radius relationship of solitons in scalar dark matter and accurately capture the deviations of this relationship from the SP system towards the KGE one.

EXCITED STATES OF DE SITTER SPACE SCALAR FIELDS: LATTICE SCHRÖDINGER PICTURE

2006 ◽  
Vol 21 (22) ◽  
pp. 1717-1725 ◽  
Author(s):  
JUNG-JENG HUANG
Keyword(s):  
Scalar Field ◽  
Excited States ◽  
Momentum Space ◽  
Scalar Fields ◽  
De Sitter Space ◽  
De Sitter ◽  
Minimal Coupling ◽  
Real Scalar ◽  
Schrödinger Picture

In lattice Schrödinger picture, the wave functionals of a free real scalar field in de Sitter space for the Bunch–Davies vacuum and the corresponding excited states are given explicitly in momentum space for the following coupling cases: (i) massless conformal couplng, (ii) massless minimal coupling, and (iii) massive minimal coupling. Implications of these solutions for inflationary scenarios in cosmology are also discussed.

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