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1.
Koijam Manihar Singh 《Astrophysics and Space Science》2010,325(1):127-135
Some new interesting solutions, the dynamics, behaviour and phenomena of rotating charged perfect fluid models are investigated,
and their physical and geometrical properties are studied in order to substantiate the possibility of the existence of such
astrophysical bodies in this Universe. The nature and role of the metric rotation Ω(r,t) as well as that of the matter rotation ω(r,t) are studied for uniform and non-uniform motions. The reactions of the gravitational and charged fields with respect to the
rotational motion are studied and possible results are explored for real astrophysical situations, and in some solutions we
find the spatial restrictions on the models for realistic conditions. Rotating models which are expanding are obtained in
which the rotational motions are decaying with time. 相似文献
2.
Koijam Maniharsingh 《Astrophysics and Space Science》1990,164(1):153-166
In the course of presentation of several new analytic solutions, the dynamics of slowly rotating magnetoviscous-fluid distribution is investigated. The nature and role of the rotational velocity (r, t) which is related to the local dragging of inertial frames and that of matter rotation (r, t) are studied for uniform and non-uniform motions. It is observed that the magnetic field decays the rotational motion and this damping effect is found to be roughly analogous to viscosity. Rotating models which are expanding as well are obtained, which may be taken as good examples of real astrophysical situations; and their geometrical and physical properties are discussed in detail. 相似文献
3.
Koijam Maniharsingh 《Astrophysics and Space Science》1991,183(2):285-307
Along with the presentation of several new analytic solutions, the dynamics of slowly rotating perfect-fluid model universes are investigated, and their physical and geometrical properties are discussed from all angles. The rotational perturbations of such models are examined in detail in order to substantiate the possibility that the Universe is endowed with some rotation. The nature and role of the rotational velocity (r, t) which is related to the local dragging of inertial frames and that of the matter rotation (r, t) are studied for uniform and non-uniform motions. We find out the restrictions on the radii of the models for real astrophysical situations, and the periods of physical validity of them are also obtained. Rotating models which are expanding as well are obtained, in which cases the rotational velocities are found to decay with the time; and these models may be taken as examples of real astrophysical objects in this Universe. 相似文献
4.
Koijam Maniharsingh 《Astrophysics and Space Science》1991,182(1):141-153
The dynamics of particle creation in the slowly rotating Robertson-Walker universe is studied by use of the Brans-Dicke theory, and four interesting solutions are obtained. Along with the discussion of the nature of the gravitational constant and other physical parameters in these model universes, the behaviour of these solutions with respect to Dirac's hypotheses are investigated. Also it is found that the expansion law is determined by the particles created by the expansion itself. Except for the case of a flat universe, the metric rotation as well as the matter rotation is found to have a damping effect on the creation of particles. 相似文献
5.
KJ. Maniharsingh 《Astrophysics and Space Science》1993,205(2):259-276
Radiating anisotropic two-fluid model universes coupled with a scalar field when a slow rotation is introduced in them are studied here, where the anisotropic pressure is generated by the presence of two non-interacting perfect fluids which are in relative motion with respect to each other. Special discussion is made of the physically interesting class of models in which one fluid is a comoving radiative perfect fluid which is taken to model the cosmic microwave background and the second a non-comoving perfect fluid which will model the observed material content of the Universe. Here we take up four analytic solutions. The effects of rotation on these models are studied and the reactions of the scalar and the radiation fields with respect to the rotational motion are discussed. Analysis on the rotational perturbations are also made, in the course of which the amount of anisotropy induced in the pressure distribution by a small deviation from the Friedmann metric is also investigated. It is shown that such anisotropies could grow faster than the expansion of the Universe. The rotating models we obtain here are found to be theoretically satisfactory and they may be taken as physically acceptable models. 相似文献
6.
KJ. Maniharsingh 《Astrophysics and Space Science》1993,202(2):247-257
In the course of obtaining three collapsing models of the charged viscous-fluid distribution, the dynamics of gravitational collapse are investigated with respect to them, and their physical and geometrical properties are studied critically, In all the cases, with a proper choice of the mass, the interior solution can be matched to the exterior Schwarzschild vacuum solution, thereby the solution being continuous at the boundary of the star. In all these models the matter inside is found to be radiating thus giving us the opportunity of identifying the gravitational collapse of a realistic astrophysical object. At the boundary of these model stars the matter distribution comes out to be that of dust and thereby comoving with respect to the coordinate system used. All the models are seen to be physically acceptable; they come out to be realistic models of collapsing astrophysical objects which will be of much interest in studying the phenomenon of black holes in this Universe. 相似文献
7.
Koijam Maniharsingh 《Astrophysics and Space Science》1991,180(2):253-271
The dynamics of slowly rotating magneto-viscous fluid universe coupled with zero-mass scalar field is investigated, and the rotational perturbations of such models are studied in order to substantiate the possibility that the Universe is endowed with slow rotation, in the course of presentation of several new analytic solutions. Four different cases are taken up in which the nature and role of the metric rotation (r, t) as well as that of the matter rotation(r,t) are discussed. Except for the case of perfect drag, the scalar field is found to have a damping effect on the rotational motion. This damping effect is seen to be roughly analogous to the viscosity. The periods of physical validity of some of the models are also found out. Most of the rotating models obtained here come out to be expanding ones as well which may be taken as good examples of real astrophysical situations. 相似文献
8.
The solution of three new interesting studies,a rotating anisotropic twofluid universe coupled with radiation and a scalar field,are studied here,where the anisotropic pressure is generated by the presence of two non-interacting perfect fluids which are in relative motion with respect to each other.In this problem,special discussion is made of the physically interesting class of models in which one fluid is a perfect comoving radiative fluid which is taken to model the cosmic microwave background and the se... 相似文献
9.
Koijam Manihar Singh 《Astrophysics and Space Science》2009,323(3):297-306
Presenting some interesting new solutions, rotating models of anisotropic two-fluid universes coupled with a magnetic field
are investigated and studied, where the anisotropic pressure is generated by the presence of two non-interacting perfect fluids
which are in relative motion with respect to each other. Here special discussion is made of the physically interesting class
of models in which one fluid is a comoving radiative perfect fluid which is taken to model the cosmic microwave background
and the second a non-comoving perfect fluid which will model the observed material content of the universe. Besides studying
their physical and dynamical properties the effects of rotation on these models are studied and the reactions of the magnetic
and gravitational fields with respect to the rotational motion are discussed. Analysis on the rotational perturbations are
also made, in the course of which the amount of anisotropy induced in pressure distribution by a small deviation from the
Friedmann metric is also investigated. The models obtained here are found to be theoretically satisfactory and thereby substantiates
the possibilities of existence of such astrophysical objects in this Universe and may be taken as good examples of real astrophysical
situations. 相似文献
10.