Aharonov-Bohm and non-inertial effects on a Klein-Gordon oscillator with potential in the cosmic string space-time with a spacelike dislocation

In this paper, we investigate the analogue effect to the Aharonov-Bohm effect for bound states in a relativistic quantum system described by the Klein-Gordon oscillator in the cosmic string space-time with a spacelike dislocation. We assume the topological defects have an internal magnetic flux and then analyze the effect on the relativistic energy eigenvalue subject to a Cornell-type potential and subsequently with a Coulomb-type potential. We show the presence of various potential parameters, the torsion parameter as well the cosmic string modify the energy spectrum.     

Cosmic inflation and cosmic string

We discuss the evolution of inhomogeneous space-time with a spinning fluid in higher dimensions. Using these evolving solutions, we explain cosmic inflation and the formation of a gravitational nontopological cosmic string.     

Zitterbewegung in the AdS Cosmic String Space-Time

Russian Physics Journal - We consider the Zitterbewegung (ZB) effect induced in the AdS (anti-de Sitter) space-time by a cosmic string. Near the cosmic string, the effects of curvature play a...     

Strong Field Gravitational Lensing in a Magnetic Charged Reissner-Nordstr?m Black Hole Pierced by a Cosmic String

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.     

Pair production in the gravitational field of a cosmic string

We show that many elementary particle physics processes, such as pair production by a high energy photon, that take place in Minkowski space only if a non-uniform external field provides for momentum non-conservation, do occur in the space-time around a straight cosmic string, even though the space is locally flat and there is no local gravitational potential. We exemplify this mechanism through the evaluation of the cross section per unit length of string for the decay of a massless scalar particle into a pair of massive particles. The cross sections for this kind of processes are typically small. Nevertheless, it is interesting to realize how these reactions occur due to topological properties of space, rather than to the action of a local field.     

Test particle trajectories near cosmic strings

We present a detailed analysis of the motion of test particle in the gravitational field of cosmic strings in different situations using the Hamilton-Jacobi (H-J) formalism. We have discussed the trajectories near static cosmic string, cosmic string in Brans-Dicke theory and cosmic string in dilaton gravity.     

Superconducting cosmic strings. II. Spacetime curvature

We solve the Einstein-Maxwell and scalar field equations for an infinitely long bosonic superconducting cosmic string and explore the associated geometry of space-time. The metric describing the space-time is valid for both fermionic and bosonic superconducting cosmic strings. Due to general relativistic corrections, the magnetic field energy per unit length associated with the string does not diverge. A non-uniform charged Higgs field contribution to the stress-energy tensor endows the string with an effective mass that enables to attract gravitationally and alters its lensing properties.     

Cosmic microwave background anisotropy induced by a moving straight cosmic string

A method of searching for cosmic strings based on an analysis of the cosmic microwave background (CMB) anisotropy is presented. A moving straight cosmic string is shown to generate structures of enhanced and reduced brightness with a distinctive shape. The conditions under which a string can be detected by both CMB anisotropy and gravitational lensing in optical surveys are analyzed. For a relativistic string with a deficit angle of ～1″–2″, the amplitude of the generated anisotropy is shown to be ～15–30 μK.     

Radio jets and galaxies as cosmic string probes

The lensing effect of a cosmic string is studied, and some new methods are proposed to detect the cosmic string. The technique for using jets as extended gravitational lensing probes was first explored by Kronberg.We use the “alignment-breaking parameter” ηG as a sensitive indicator of gravitational distortion by a wiggly cosmic string. Then, we applied the non-constant deflection angle to jets, and ηG of a specific jet is just related to the projected slope of the jet. At least three jets in the sample of Square Kilometer Array (SKA) would have significant signals (ηG>10°) if the wiggly infinite cosmic string existed. The distortion of elliptical object is also studied and used to do a statistical research on the directions of axes and ellipticities of galaxies. In the direction of the string, we find that galaxies appear to be more elliptical for an observer and the distribution of apparent ellipticity changes correspondingly. The ellipticity distribution of current SDSS spiral sample has the signalto-noise ratio up to 8.48 which is large enough for astronomical observations. The future survey, such as Large Synoptic Survey Telescope (LSST) and Dark Energy Survey (DES) would weaken the requirement of special geometry in the data processing. As a result, all kinds of distributions, including ellipticity axis distribution, would serve as probes to detect wiggly strings in the near future. In brief, if a wiggly cosmic string existed, these signals would be convenient to be observed with the future weak lensing survey or other surveys in the deep space. If there was no lensing signal in these distributions, it would give the upper limit of the abundance of infinite strings.     

Dynamical properties of superconducting cosmic strings: (II). Heavy closed strings in magnetic field

We discuss a circular static superconducting cosmic string in a homogeneous magnetic field and show that the mass is independent of the radius provided we choose a GUT scale as well as a reasonable value for the intergalactic magnetic field. A conservative estimate gives a mass of order 10¹⁶ M_⊙. We also discuss various gravitational effects related to this string. The most striking effect is the gravitational lens effect that can produce four images.     

Strings and statistics

We discuss the possibility of unusual statistics in four dimensional string theory through the use of Aharonov-Bohm like phases. Such phases are closely related to anomaly cancellation in four dimensions and thus can be exactly calculated in terms of the low energy fermion spectrum of the theory. We illustrate this connection by calculating the statistical phases exactly in sample models of heterotic string compactification. We discuss some of the difficulties in applying these ideas to fundamental strings, and mention some possible applications to cosmic string scenarios.     

Spherically Symmetric Cosmic Strings in Bimetric Theory

Spherically symmetric space-time is considered in bimetric theory of gravitation formulated by Rosen (Gen. Relativ. Gravit. 4:435, [1973]) in the presence of perfect fluid, massive scalar field and cosmic string. It is shown that either macro cosmological model represented by perfect fluid or cosmic string do not exist and only a vacuum model can be constructed whereas in case of a micro cosmological model represented by a scalar field exists and the model is obtained.     

A multipolar stationary object attached to a cosmic string in a background gravitational field

We present in this paper an exact solution of a multipolar stationary object attached to a string embedded in a background gravitational field. Under certain conditions the string may be interpreted as a cosmic string.     

Stretching of a Cosmic String in the Presence of a Vacuum Domain Wall

It is shown that the domain wall pumps a cosmic string in its gravitational field with a gravitational energy. This increases the tension energy and results in the string straightening. The process of straightening is a new physical mechanism of cosmic-string stretching.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 20–26, April, 2005.     

The static metrics with cylindrical symmetry describing a model of cosmic strings

We discuss a set of static metrics with cylindrical symmetry describing the interior and exterior space-time of a model of cosmic strings considered recently in cosmology. The interior metric depends on one arbitrary function and the exterior on one constant. We find the relation between this constant and the linear mass density of the cosmic string. A cosmic string can be also treated as a line source in the framework of the distribution-valued curvature formalism which allows us to obtain again the same relation.     

Berry’s phase for a spin 1/2 particle in the presence of topological defects

The relativistic quantum dynamics of a spinorial quantum particle in the presence of a chiral conical background is investigated. We study the gravitational Berry geometric quantum phase acquired by a spin 1/2 particle in the chiral cosmic string spacetime. We obtain the result that this phase depends on the global features of this spacetime. We also consider the case that a string possesses an internal magnetic flux and obtain the geometric quantum phase in this case. The spacetime of multiple chiral cosmic strings is considered and the relativistic Berry quantum phase is also obtained.     

Modelling background radiation in isotropic cosmologies

Using explicit perturbations of isotropic cosmological models which describe simple gravitational waves, an isotropic tensor having the algebraic symmetries of the Bel–Robinson tensor is derived as a model of cosmic background gravitational radiation and this is used to provide an answer to the question: in what sense can an energy–momentum–stress tensor similar to that describing the cosmic microwave background radiation (neglecting anisotropies) be associated with an isotropic background of gravitational radiation?     

Solving the hierarchy problem with noncompact extra dimensions

We show that gravitational effects of global cosmic 3-branes can be responsible for compactification from six to four space-time dimensions, naturally producing the observed hierarchy between electroweak and gravitational forces. The finite radius of the transverse dimensions follows from Einstein's equation, and is exponentially large compared with the scales associated with the 3-brane. The space-time ends on a mild naked singularity at the boundary of the transverse dimensions; nevertheless unitary boundary conditions render the singularity harmless.     

Discrete Spectrum of the Deficit Angle and the Differential Structure of a Cosmic String

Differential properties of Klein-Gordon and electromagnetic fields on the space-time of a straight cosmic string are studied with the help of methods of the differential space theory. It is shown that these fields are smooth in the interior of the cosmic string space-time and that they loose this property at the singular boundary except for the cosmic string space-times with the following deficit angles: Δ=2π(1−1/n), n=1,2,… . A connection between smoothness of fields at the conical singularity and the scalar and electromagnetic conical bremsstrahlung is discussed. It is also argued that the smoothness assumption of fields at the singularity is equivalent to the Aliev and Gal’tsov “quantization” condition leading to the above mentioned discrete spectrum of the deficit angle.     

The Sagnac effect in curved space-times from an analogy with the Aharonov-Bohm effect

In the context of the natural splitting, the standard relative dynamics can be expressed in terms of gravito-electromagnetic fields, which allow to formally introduce a gravito-magnetic Aharonov-Bohm effect. We showed elsewhere that this formal analogy can be used to derive the Sagnac effect in flat space-time as a gravito-magnetic Aharonov-Bohm effect. Here, we generalize those results to study the General Relativistic corrections to the Sagnac effect in some stationary and axially symmetric geometries, such as the space-time around a weakly gravitating and rotating source, Kerr space-time, Gödel universe and Schwarzschild space-time.