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1.
In the previous paper (Li et al. in Phys. Lett. B 666:125–130, 2008), we show the solutions of Einstein equations with static spherically-symmetric quintessence-like matter surrounding a global monopole. Furthermore, this monopole become a black hole with quintessence-like matter and a deficit solid angle when it is swallowed by an ordinary black hole. We study its quasinormal modes by WKB method in this paper. The numerical results show that both the real part of the quasinormal frequencies and the imaginary part decrease as the state parameter w, for scalar and gravitational perturbations. And we also show variations of quasinormal frequencies of scalar and gravitational fields via different ε (deficit solid angel parameter) and different ρ 0 (density of static spherically-symmetric quintessence-like matter at r=1), respectively.  相似文献   

2.
Recently, exact spatially-homogeneous solutions have been found for a conformally invariant massless scalar fieldS(t) coupled to a Robertson-Walker geometry. We investigate extending these solutions to inhomogeneous scalar fieldsS(t, x l ). For an isotropic scalar fieldS(t, r) we find a solution satisfying three of the five field equations. If we use REDUCE, we show that the remaining equations forceS=S(t).  相似文献   

3.
FIEDLER and SCHIMMING (1983) proved that the fourth order gravitational field equations with a linear combination of Bach's and Einstein's tensors on the left-hand side, which were proposed by TREDER , admit static centrally symmetric solutions which are analytical and non-flat in some neighbourhood of the centre of symmetry. The existence of these solutions, known at first only in a small neighbourhood of r = o (r radius), can now be extended to intervals o ≦ r ≦ α with arbitrarily large α , using the abstract theorem on inverse functions. Further it is proved that the Schwarzschild metrics are in a certain sense the only solutions of the above equations that are analytic, asymptotically flat, static and centrally symmetric around r = +∞.  相似文献   

4.
Static spherically symmetric anisotropic source has been studied for the Einstein-Maxwell field equations assuming the erstwhile cosmological constant Λ to be a space-variable scalar, viz., Λ=Λ(r). Two cases are examined out of which one reduces to isotropic sphere. The solutions thus obtained are shown to be electromagnetic in origin as a particular case. It is also shown that the generally used pure charge condition, viz., ρ+p=0 is not always required for constructing electromagnetic mass models.  相似文献   

5.
The Bach-Einstein equation linearized around Minkowski space-time is completely solved. The set of solutions depends on three parameters; a two-parameter subset of it becomes asymptotically flat. In that region the gravitational potential is of the type φ = -m/r + ε exp (-r/l) m and ε being small parameters. Because of the different asymptotic behaviour of both terms, it became necessary to linearize also around the Schwarzschild solution φ = -m/r. The linearized equation resulting in this case is discussed using qualitative methods. The result is that for m ≤ 2l the asymptotic behaviour is φ = -m/r + εr−m/l exp (-r/l) u, and for m ≧ 2l φ = -m/r + εr−2 exp (-r/l) u, where u is some bounded function; m is arbitray and ε again small. Further, the relation between the solution of the linearized and the full equation is discussed.  相似文献   

6.
We look for cosmologies with a scalar field (dark energy without cosmological constant), which mimic the standard ΛCDM cosmological model yielding exactly the same large-scale geometry described by the evolution of the Hubble parameter (i.e. photometric distance and angular diameter distance as functions on z). Asymptotic behavior of the field solutions is studied in the case of spatially flat Universe with pressureless matter and separable scalar field Lagrangians; the cases of power-law kinetic term and power-law potential are considered. Exact analytic solutions are found in some special cases. A number of models have the field solutions with infinite behavior in the past or even singular behavior at finite redshifts. We point out that introduction of the cosmological scalar field involves some degeneracy leading to lower precision in determination of Ω m . To remove this degeneracy additional information is needed besides the data on large-scale geometry. The article is published in the original.  相似文献   

7.
Green's Theorem is developed for the spherically-symmetric steady-state cosmic-ray equation of transport in interplanetary space. By means of it the momentum distribution functionF o(r,p), (r=heliocentric distance,p=momentum) can be determined in a regionr arrbwhen a source is specified throughout the region and the momentum spectrum is specified on the boundaries atr a andr b . Evaluation requires a knowledge of the Green's function which corresponds to the solution for monoenergetic particles released at heliocentric radiusr o , Examples of Green's functions are given for the caser a =0,r b = and derived for the cases of finiter a andr b . The diffusion coefficient is assumed of the form = o(p)r b . The treatment systematizes the development of all analytic solutions for steady-state solar and galactic cosmic-ray propagation and previous solutions form a subset of the present solutions.  相似文献   

8.
Several authors have studied solutions of Einstein's field equations for a conformally invariant scalar field with trace-free energy-momentum tensor for the Robertson-Walker models forK = 0, ± 1. The relationship of these solutions to a previously existing one by Som (1985) is discussed. TheK = 0 model derived by Innaiah and Reddy (1985) is shown to be a special case of the Bianchi type-I models due to Accioly, Vaidya and Som (1983a).  相似文献   

9.
The modified theories of gravity, especially the f(R) gravity, have attracted much attention in the last decade. In this context, we study the exact vacuum solutions of Bianchi type I, III and Kantowski-Sachs spacetimes in the metric version of f(R) gravity. The field equations are solved by taking expansion scalar θ proportional to shear scalar σ which gives A=B n , where A and B are the metric coefficients. The physical behavior of the solutions has been discussed using some physical quantities. Also, the function of the Ricci scalar is evaluated in each case.  相似文献   

10.
Under the assumption of a power-law between the expansion factor of the Universe, and the scalar field (a n=c=const.) tensor theory with cosmological constant are reduced to quadrature. Several exact solutions are obtained, among them inflationary universes that have barotropic equation of state.  相似文献   

11.
The inertial effect on the structure of the magnetosphere of a rotating star is investigated, in the corotation approximation for a surrounding quasi-neutral plasma. The equation of motion reduces to a usual static balance equation between the electromagnetic and the centrifugal forces, in the rotating frame. However the MHD condition, which can be regarded as a special form of the generalized Ohm's law, is modified by the inclusion of inertial effect, with a violation of the frozen-in condition in case of a general (i.e., not restricted to corotation) plasma motion. The inertial effect on the electromagnetic field is summarized in a partial scalar potential named the non-Backus potential, which is proportional to the centrifugal potential in the corotation approximation.An approximate solution of this corotation problem is given, in which another characteristic radiusr M appears besides the light radiusr L . This radius defines a distance beyond which the inertial effect becomes dominant over the electromagnetic one, and is useful in estimating the magnitude of the terminal velocity of a centrifugal wind. A few examples of the modification of dipole magnetic field due to the inertial effect are visualized. In an oblique-rotation case, it can be seen that such a warp of the neutral sheet (the surface ofB r =0) is reproduced as observed in the Jovian magnetosphere.  相似文献   

12.
A new version of the magnetic-tape catalog of ABELL clusters of galaxies is used to obtain redshift estimators and to generate two samples of clusters. A procedure for searching for superclusters of galaxies is applied and the results are given in tabular and graphic form. For a lmited homogeneous sample (distance 60–275 Mpc, galactic latitude B > 35°), 12 multiplets, having member clusters with known redshifts, are found. It is shown that the spatial covariance function for rich clusters has the form ξ = (r0/r)γ with r0 = 22.4 ± 1.8 Mpc and γ = 1.90 ± 0.25 for 3 Mpc ≲ r ≲ 80 Mpc.  相似文献   

13.
For z = 0.8–2.2 redshift interval, quasar pair correlation function parameters and β redshift space distortion parameter (connected to large-scale potential flows) values are estimated. We base them on the Main QSO Sample from SDSS Data Release 5. Standard correlation function form ξ(r) = (r 0/r)γ is used for comoving distances r = 2–50 Mpc between quasars. We fix the parameters of the cosmological model: ΩΛ = 1 − Ω M = 0.726 and H 0 = 70.5 km/(s Mpc). We come to the best-fit parameter values of γ = 1.77 ± 0.20, r 0 = 5.52 ± 0.95 Mpc/h for r in the range 2–30 Mpc, γ = 1.91 ± 0.11, r 0 = 5.82 ± 0.61 Mpc for r in the range 2–50 Mpc. The mean β value is β = 0.43 ± 0.22.  相似文献   

14.
String cosmological models with bulk viscosity are investigated in Kantowski-Sachs space-time. To obtain a determinate solution, it is assumed that the coefficient of bulk viscosity is a power function of the scalar of expansion ζ = kθm and the scalar of expansion is proportional to the shear scalar θ ∝ σ, which leads to a relation between metric potentials R = AS n . The physical and geometrical aspects of the model are also discussed. It is shown that the bulk viscosity has significant influence on the evolution of the universe. There is a ‘big bang’ start in the model when m ≤ 1 but there is no ‘big bang’ start when m > 1.  相似文献   

15.
In this paper some wormhole solutions have been presented on the brane which are distinct from the presently available wormhole solution. The matter on the brane is chosen as perfect fluid and all physical variables are functions of the radial co-ordinate r. The solutions are obtained considering the trace of the resulting matter i.e. the Ricci scalar on the brane to be zero.  相似文献   

16.
Multi-dimensional cosmological models with n(n > 1) Ricci-flat spaces and a scalar field are discussed classically and with respect to canonical quantization. These models are integrable. Two classes of solutions are obtained. One class of solutions generalizes the Kasner solutions. For special additional conditions we find another solution describing extended inflation connected with a constant volume of the whole multidimensional space (steady-state).  相似文献   

17.
We investigate in this paper the dynamics of Born-Infeld (B-I) type dark energy model with scalar potential $V_{0}e^{-\beta\varphi^{2}}$ , and consider the new statefinder diagnostic to differentiate B-I type dark energy model from LCDM which corresponds to statefinder pair {r,s}={1,0}. We study the existence of attractor solution in this model and the evolving trajectory of r?s in our model with this scalar potential. It is numerically shown that the evolving trajectory of r?s is quite different from those of other dark energy models.  相似文献   

18.
The scalar field theory on the background of cosmological models with n(n ≥ 1) spaces of constant curvature is considered. We take the integrable case of Ricci flat internal spaces. The coupling between the scalar and the gravitational fields includes the minimal coupling as well as the conformal case. In the ground state of the scalar field we find the conditions for vacuum instability realized for most of the possible solutions to Einstein's equations if the coupling parameter takes appropriate values. For the excited states of the scalar field we show the induction of massive modes and discuss their properties.  相似文献   

19.
An exact solution has been obtained for the Einstein-Maxwell field equation with corresponding to a spherically-symmetric charged perfect fluid distribution. Here the cosmological constant is assumed to be a scalar variable depending on the radial coordinater of the spherical system, viz., = (r). The solution set thus obtained presents an electromagnetic mass model.  相似文献   

20.
An (E, R, , ) summation method is a summability procedure which can be used for purposes of analytic continuation. In this paper the solutions of the hyperbolic two-body problem are used as a test case for the methods (E, r, 0, 1) and (E, r, 0, 2) and effective continuation of the solutions is obtained  相似文献   

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