相关论文: Flat wormholes from straight cosmic strings

The special Buchdahl-inspired metric obtained in a recent paper [Phys. Rev. D 107, 104008 (2023)] describes asymptotically flat spacetimes in pure $\mathcal{R}^{2}$ gravity. The metric depends on a new (Buchdahl) parameter $\tilde{k}$ of…

The aim of these lectures is to give an introduction to several topics which lie at the intersection of string theory, gravity theory and gravity phenomenology. One successively reviews: (i) the "membrane" approach to the dissipative…

We fully classify the phenomenology of gravitational wave emission from scaling cosmic string networks with varying tension and compute the spectral indices of the resulting stochastic backgrounds. In string compactifications, periods of…

The Kerr-Schild (KS) geometry is linked tightly with the auxiliary \emph{flat} Minkowski background. Nevertheless, it describes many curved space-times and the related physical models, starting from cosmology and black holes to the…

We consider the possible existence of gravitationally bound stringlike objects in the framework of the generalized hybrid metric-Palatini gravity theory, in which the gravitational action is represented by an arbitrary function of the Ricci…

Cosmic strings represent an attractive source of gravitational waves (GWs) from the early Universe. However, numerical computation of the GW signal from cosmic strings requires the evaluation of complicated integral and sum expressions,…

It is well-known that traversable wormhole solutions to the Einstein equations require the existence of an exotic matter source violating the null energy condition. An apparent exception is the overcharged Kerr-Newman-NUT solution of the…

Black holes, the simplest solution to Einstein's field equations, do not emit light, making their observations a major challenge for researchers. However, discovery of binary black holes (BBHs) in 2015 by LIGO has transformed the study of…

An attempt has been made to have an analytical description for possible traversable wormhole in non-static spherically symmetric space-time supported by anisotropic fluid. Both trivial and non-trivial choices of the red-shift function…

Cosmic strings are linear concentrations of energy that form whenever phase transitions in the early universe break axial symmetries as originally shown by Kibble. They are the result of frustrated order in the quantum fields responsible…

We investigate scaling and correlations of the energy and momentum in an evolving network of cosmic strings in Minkowski space. These quantities are of great interest, as they must be understood before accurate predictions for the power…

Cosmic strings are predicted by many field-theory models, and may have been formed at a symmetry-breaking transition early in the history of the universe, such as that associated with grand unification. They could have important…

We construct a four-dimensional spacetime using a three-dimensional contact manifold equipped with a degenerate metric. The degenerate metric is set to be compatible with the contact structure. The compatibility condition is defined in this…

We present a simple sandwich gravitational wave of the Robinson-Trautman family. This is interpreted as representing a shock wave with a spherical wavefront which propagates into a Minkowski background minus a wedge. (i.e. the background…

Using thin shell formalism we construct two solutions of intra-universe wormholes. The first model is a cosmological analog of the Aichelburg-Schein timehole, while another one is an intra-universe form of the Bronnikov-Ellis solution.

In the present work we investigate wormhole configurations described by a constant redshift function in Einstein-Cubic gravity ({{\sf ECG}}). We derive analytical wormhole geometries by assuming a particular equation of state ({{\sf EoS}})…

We develop ambitwistor string theories for 4 dimensions to obtain new formulae for tree-level gauge and gravity amplitudes with arbitrary amounts of supersymmetry. Ambitwistor space is the space of complex null geodesics in complexified…

We study spherically symmetric thin-shell wormholes in a string cloud background in (3+1)-dimensional spacetime. The amount of exotic matter required for the construction, the traversability and the stability under radial perturbations, are…

This paper investigates a particular type of wormhole. The wormholes studied are the result of sewing together two Reissner-Nordstrom-type black hole metrics at their horizons. By requiring the stress-energy tensor associated with this…

We study the classical and quantum wormholes for a flat {\it Euclidean} Friedmann-Robertson-Walker metric with a perfect fluid including an ordinary matter source plus a source playing the role of dark energy (decaying cosmological term).…