scholarly journals Thin accretion discs around spherically symmetric configurations with nonlinear scalar fields

2021 ◽  
Vol 104 (10) ◽  
Author(s):  
O. S. Stashko ◽  
V. I. Zhdanov ◽  
A. N. Alexandrov
Keyword(s):  
Scalar Fields ◽  
Accretion Discs ◽  
Spherically Symmetric

scholarly journals 4D STATIC SOLUTIONS WITH INTERACTING PHANTOM FIELDS

2008 ◽  
Vol 17 (11) ◽  
pp. 2125-2142 ◽  
Author(s):  
VLADIMIR DZHUNUSHALIEV ◽  
VLADIMIR FOLOMEEV
Keyword(s):  
Scalar Fields ◽  
Spherically Symmetric ◽  
Symmetric Problem ◽  
Regular Solutions ◽  
Traversable Wormhole ◽  
Static Solutions ◽  
Static Models ◽  
Phantom Fields

Three static models with two interacting phantom and ghost scalar fields are considered: a model of a traversable wormhole, a branelike model and a spherically symmetric problem. It is shown numerically that regular solutions exist for all three cases.

Spherically symmetric scalar fields

1991 ◽  
Vol 32 (9) ◽  
pp. 2468-2472 ◽  
Author(s):  
Taxiarchis Papacostas
Keyword(s):  
Scalar Fields ◽  
Spherically Symmetric

scholarly journals Field of a charged particle in the presence of scalar meson fields in general relativity

1983 ◽  
Vol 24 (4) ◽  
pp. 461-465 ◽  
Author(s):  
D. R. K. Reddy ◽  
V. U. M. Rao
Keyword(s):  
Charged Particle ◽  
Point Charge ◽  
Scalar Meson ◽  
Scalar Fields ◽  
Flat Space ◽  
Spherically Symmetric ◽  
Conformally Flat ◽  
Field Equations ◽  
Conformally Flat Metric ◽  
Scalar Meson Field

AbstractField equations for coupled gravitational and zero mass scalar fields in the presence of a point charge are obtained with the aid of a static spherically symmetric conformally flat metric. A closed from exact solution of the field equations is presented which may be considered as describing the field of a charged particle at the origin surrounded by the scalar meson field in a flat space-time.

scholarly journals STATIC SPHERICALLY SYMMETRIC SCALAR FIELD SPACETIMES WITH C0 MATCHING

2011 ◽  
Vol 26 (17) ◽  
pp. 1281-1290 ◽  
Author(s):  
SWASTIK BHATTACHARYA ◽  
PANKAJ S. JOSHI
Keyword(s):  
Scalar Field ◽  
Naked Singularity ◽  
Scalar Fields ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Spherically Symmetric ◽  
Curvature Singularity ◽  
Einstein Theory ◽  
Full Class ◽  
Strong Curvature

All the classes of static massless scalar field models currently available in the Einstein theory of gravity necessarily contain a strong curvature naked singularity. We obtain here a family of solutions for static massless scalar fields coupled to gravity, which does not have any strong curvature singularity. This class of models contain a thin shell of singular matter, which has a physical interpretation. The central curvature singularity is, however, avoided which is common to all static massless scalar field spacetime models known so far. Our result thus points out that the full class of solutions in this case may contain non-singular models, which is an intriguing possibility.

scholarly journals Quasi-black holes: General features and purely field configurations

2015 ◽  
Vol 30 (30) ◽  
pp. 1550154 ◽  
Author(s):  
K. A. Bronnikov ◽  
O. B. Zaslavskii
Keyword(s):  
Black Holes ◽  
Small Parameter ◽  
Exact Solutions ◽  
Scalar Fields ◽  
Spherically Symmetric ◽  
Material Source

Objects that are on the threshold of forming the horizon but never collapse are called quasi-black holes (QBHs). We discuss the properties of the general spherically symmetric QBH metric without addressing its material source, including its limiting cases as the corresponding small parameter tends to zero. We then show that QBHs can exist among self-gravitating configurations of electromagnetic and dilatonic scalar fields without matter. These general results are illustrated by explicit examples of exact solutions.

scholarly journals SPHERICALLY SYMMETRIC MASSIVE SCALAR FIELDS IN GENERAL RELATIVITY

2010 ◽  
Vol 25 (07) ◽  
pp. 1429-1438 ◽  
Author(s):  
MOHAMMAD MEHRPOOYA ◽  
D. MOMENI
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Scalar Fields ◽  
Matter Field ◽  
Massless Scalar ◽  
Special Choice ◽  
Spherically Symmetric ◽  
Elementary Functions ◽  
Field Equations ◽  
Tidal Forces

First, we review some attempts made to find the exact spherically symmetric solutions to Einstein field equations in the presence of scalar fields. Wyman's solution in both the static and the nonstatic scalar field is discussed, and it is shown why in the case of the nonstatic homogenous matter field the static metric cannot be represented in terms of elementary functions. We mention here that if the space–time is static, according to field equations, there are two options for fixing the scalar field: static (time-independent) and nonstatic (time-dependent). All these solutions are limited to the minimally coupled massless scalar fields and also in the absence of the cosmological constant. Then we show that if we are interested to have homogenous isotropic scalar field matter, we can construct a series solution in terms of the scalar field's mass and cosmological constant. This solution is static and possesses a locally flat case as a special choice of the mass of the scalar field and can be interpreted as an effective vacuum. Therefore, the mass of the scalar field eliminates any locally gravitational effect as tidal forces. Finally, we describe why this system is unstable in the language of dynamical systems.

Some interactions of spherically symmetric massive scalar field with Brans–Dicke scalar field in Robertson–Walker universe

2019 ◽  
Vol 16 (04) ◽  
pp. 1950066 ◽  
Author(s):  
Kangujam Priyokumar Singh ◽  
Rajshekhar Roy Baruah
Keyword(s):  
Scalar Field ◽  
Cosmic Time ◽  
Scalar Fields ◽  
Cosmological Term ◽  
Physical Parameters ◽  
Spherically Symmetric ◽  
Massive Scalar ◽  
Field Equations ◽  
Massive Scalar Field ◽  
The Universe

Here in this work, we investigated the possible cosmological consequences of the interaction of Brans–Dicke scalar field and massive scalar field by considering spherically symmetric Robertson–Walker metric. The present problem can also be treated as an extension work of [K. Priyokumar et al., Interaction of gravitational field and Brans–Dicke field, Res. Astron. Astrophys. 16(4) (2016) 64; K. Priyokumar and M. Dewri, Interaction of electromagnetic field and Brans–Dicke field, Chinease J. Phys. 54 (2016) 845]. The exact solutions of the field equations are obtained with seven different cases. The behavior of the model and their contribution to the process of the evolution are examined in detail from some explicit and reasonable values of free parameter. We also presented the variations of certain physical parameters versus cosmic time graphically to compare our solutions with the present observational findings. When we studied further, it is found that the cosmological term [Formula: see text] takes a great role in the accelerating expansion of our universe when both scalar fields are exponentially increasing functions of time, while the cosmological term will not appear in the case when both the scalar fields are exponentially decreasing functions of time. Also, the scalar field is seen to have a tendency to increase the expansion of the universe, thereby flattening the universe.

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