共查询到20条相似文献,搜索用时 20 毫秒
1.
Spatially homogeneous Bianchi types V and VI0 cosmological models are studied with source cosmic cloud strings coupled with electromagnetic field in Rosen’s (Gen. Relativ.
Gravit. 4:435, 1973) bimetric theory of relativity. It is observed that Bianchi type V space time is feasible whereas Bianchi type VI0 is not feasible. In the feasible case different equations of state for cosmic strings with Maxwell fields do not survive
in this theory and the space-time turns out to be flat. 相似文献
2.
K. S. Adhav M. V. Dawande V. B. Raut 《International Journal of Theoretical Physics》2009,48(3):700-705
Bianchi type III space time is considered in the presence of cosmic strings in Einstein’s general theory of relativity. Exact
cosmological models are presented with the help of relation C=B
n
between metric coefficients C and B. Some physical properties of the model in each cases are discussed. 相似文献
3.
K. S. Adhav P. S. Gadodia A. S. Bansod 《International Journal of Theoretical Physics》2011,50(9):2720-2736
Hoyle-Narlikar C-field has been introduced to study cosmic strings in Bianchi type-I space-time. The solutions have been studied when the
creation field C is a function of time t only. The geometrical and physical aspects for the models have also been studied. 相似文献
4.
Mahesh Kumar Yadav Anju Rai Anirudh Pradhan 《International Journal of Theoretical Physics》2007,46(11):2677-2687
We investigate the integrability of cosmic strings in Bianchi III space-time in presence of a bulk viscous fluid by applying
a new technique. The behavior of the model is reduced to the solution of a single second order nonlinear differential equation.
We show that this equation admits an infinite family of solutions. Some physical consequences from these results are also
discussed. 相似文献
5.
K. S. Adhav V. B. Raut M. V. Dawande 《International Journal of Theoretical Physics》2009,48(4):1019-1029
Bianchi type-III space time is considered in the presence of cosmic strings and thick domain walls source in the frame work
of general relativity. Exact cosmological models using various cases of ρ=α
λ and p=γ
ρ are presented. It is observed that the behavior of these models (with cosmic strings and domain walls), based on their physical
and kinematical properties, is found to be identical. 相似文献
6.
We investigate the integrability of cosmic strings in Bianchi II, VIII and IX space-times using a Lie symmetry analysis. The
behaviour of the gravitational field is governed by solutions of a single second order nonlinear differential equation. We
demonstrate that this equation is integrable and admits an infinite family of physically reasonable solutions. Particular
solutions obtained by other authors are shown to be special cases of our class of solutions. 相似文献
7.
We investigate the integrability of cosmic strings in Bianchi III spacetime using a symmetry analysis. The behaviour of the
model is reduced to the solution of a single second order nonlinear differential equation. We show that this equation has
a rich structure and admits an infinite family of solutions. Our class of solutions extends special cases previously obtained
by Tikekar and Patel [Gen. Relativ. Gravit.
24, 397 (1992)]. 相似文献
8.
A Bianchi type-I cosmological model in the presence of a magnetic flux along a cosmic string is investigated. A nonlinear
spinor field is used to simulate the cosmological cloud of strings. It is shown that the spinor field simulation offer the
possibility to solve the system of Einstein’s equation without any additional assumptions. It is pointed out that the present
model is nonsingular at the end of the evolution and does not allow the anisotropic Universe to turn into an isotropic one. 相似文献
9.
The Einstein field equations of massive strings are solved completely with and without a source free magnetic field for the Bianchi type I metric in a different basic form. Some physical properties of the models are studied. 相似文献
10.
We will study the cosmological implications of the five dimensional scalar–vector and scalar-Kalb–Ramond model. In particular, a new set of Bianchi type I power-law analytic solution will be obtained for this model. The cosmic no-hair conjecture can be shown to break down in the presence of the scalar–vector and scalar-Kalb–Ramond couplings. The effect of the Kalb–Ramond field in the presence of the power-law solution will be shown explicitly. We will also show that the presence of a phantom field does, however, destabilize the corresponding Bianchi type I power-law inflationary solutions. 相似文献
11.
K. S. Adhav A. S. Nimkar V. G. Mete M. V. Dawande 《International Journal of Theoretical Physics》2010,49(5):1127-1132
Axially symmetric Bianchi type-I space time is considered in the presence of massless scalar field and cosmic strings in Barber’s
(Gen. Relativ. Gravit. 14:117, 1982) self-creation theory with two conditions (i) A=B
n
and (ii) ε+λ=0. Some physical and kinematical properties of the model, thus obtained, are also discussed. 相似文献
12.
The Bianchi type-II cosmological solutions of massive strings have been investigated in the presence as well as absence of
the magnetic field. The energy conditions for a cloud of strings coupled to the Einstein equations have been examined. The
physical features of the models have also been discussed. 相似文献
13.
《Nuclear Physics B》1995,456(3):622-632
We begin a search for nonsupersymmetric/supersymmetric dual string pairs by constructing candidate critical nonsupersymmetric strings as solitons in supersymmetric string theories. Using orbifold techniques, one can construct cosmic string solutions which lie in supersymmetric vacua but which do not fall in supermultiplets. We discuss two three-dimensional examples in detail. The effective worldsheet actions for the soliton strings have (0,2) and (1,1) supersymmetry and the correct numbers of massless bosons and fermions to be critical heterotic and type II strings, respectively. 相似文献
14.
Following the techniques used by Letelier and Stachel some new physically relevant explicit Bianchi VI0 solutions of string cosmology with magnetic field are reported. They include two models describing distributions of Takabayashi
strings and geometric strings respectively. 相似文献
15.
Axially symmetric Bianchi-I model is studied with source cosmic cloud strings coupled with electromagnetic field in Rosen’s
bimetric theory of relativity and observed that there is no contribution from cosmic strings and Maxwell fields in this theory. 相似文献
16.
We perform a multiparameter likelihood analysis to compare measurements of the cosmic microwave background (CMB) power spectra with predictions from models involving cosmic strings. Adding strings to the standard case of a primordial spectrum with power-law tilt ns, we find a 2sigma detection of strings: f10=0.11+/-0.05, where f10 is the fractional contribution made by strings in the temperature power spectrum (at l=10). CMB data give moderate preference to the model ns=1 with cosmic strings over the standard zero-strings model with variable tilt. When additional non-CMB data are incorporated, the two models become on a par. With variable ns and these extra data, we find that f10<0.11, which corresponds to Gmicro<0.7x10(-6) (where micro is the string tension and G is the gravitational constant). 相似文献
17.
Cosmic strings are linear structures of cosmological scales whose search has been actively conducted in recent years. Progress
in constructing theoretical models and investigating the properties of cosmic strings and a significant growth of observational
resources provide extensive possibilities for the search of such objects by several independent observational methods. These
methods include searching for the events of gravitational lensing of distant background sources by strings and searching for
the distinctive cosmic micro-wave background anisotropy structures induced by strings. We discuss these techniques and propose
the methods of searching for strings oriented toward the latest spacecraft, including the Planck project. 相似文献
18.
The LRS Bianchi type-I and type-II string cosmological models are studied when the source for the energy momentum tensor is a bulk viscous stiff fluid containing one dimensional strings together with zero-mass scalar field. We have obtained the solutions of the field equations assuming a functional relationship between metric coefficients when the metric is Bianchi type-I and constant deceleration parameter in case of Bianchi type-II metric. The physical and kinematical properties of the models are discussed in each case. The effects of Viscosity on the physical and kinematical properties are also studied. 相似文献
19.
Cosmic strings are theoretically predicted linear structures of a cosmological size. The search for cosmic strings in optical
and radio observations has been an important area of research in recent years. One of the most effective methods of searching
for these objects is the analysis of the anisotropy of cosmic microwave background radiation that could be induced by cosmic
strings. For this purpose, the authors propose a method of signal expansion in modified Haar functions with cyclic translations.
However, for a system of these functions to be used correctly, one needs to prove its orthonormality and completeness, which
is the purpose of this paper. 相似文献
20.
Juan Deng 《International Journal of Theoretical Physics》2012,51(5):1632-1639
The principal focus of this paper is to study the strong field gravitational lensing in a magnetic charged Reissner-Nordstr?m
black hole based on the method of cosmic string. We obtain the new coefficients including the tension of the cosmic strings,
the strong field deflection limit coefficients, the deflection angle and the magnification, and obtain the relationship between
the cosmic string parameter and the new coefficients. The result shows that the cosmic strings have some important effect
on the gravitational lensing in a black hole when they pierce it. 相似文献