A general procedure for selecting a class of fully symmetric space-time covariance functions

2016 ◽  
Vol 27 (4) ◽  
pp. 212-224 ◽  
Author(s):  
S. De Iaco ◽  
M. Palma ◽  
D. Posa
Keyword(s):  
Symmetric Space ◽  
General Procedure ◽  
Space Time ◽  
Covariance Functions

Pseudo-Z symmetric space-times with divergence-free Weyl tensor and pp-waves

2016 ◽  
Vol 13 (02) ◽  
pp. 1650015 ◽  
Author(s):  
Carlo Alberto Mantica ◽  
Young Jin Suh
Keyword(s):  
Symmetric Space ◽  
Weyl Tensor ◽  
Killing Vector ◽  
Complete Classification ◽  
Space Time ◽  
Conformal Killing ◽  
Conformally Flat ◽  
Conformal Curvature ◽  
Wave Space ◽  
Divergence Free

In this paper we present some new results about [Formula: see text]-dimensional pseudo-Z symmetric space-times. First we show that if the tensor Z satisfies the Codazzi condition then its rank is one, the space-time is a quasi-Einstein manifold, and the associated 1-form results to be null and recurrent. In the case in which such covector can be rescaled to a covariantly constant we obtain a Brinkmann-wave. Anyway the metric results to be a subclass of the Kundt metric. Next we investigate pseudo-Z symmetric space-times with harmonic conformal curvature tensor: a complete classification of such spaces is obtained. They are necessarily quasi-Einstein and represent a perfect fluid space-time in the case of time-like associated covector; in the case of null associated covector they represent a pure radiation field. Further if the associated covector is locally a gradient we get a Brinkmann-wave space-time for [Formula: see text] and a pp-wave space-time in [Formula: see text]. In all cases an algebraic classification for the Weyl tensor is provided for [Formula: see text] and higher dimensions. Then conformally flat pseudo-Z symmetric space-times are investigated. In the case of null associated covector the space-time reduces to a plane wave and results to be generalized quasi-Einstein. In the case of time-like associated covector we show that under the condition of divergence-free Weyl tensor the space-time admits a proper concircular vector that can be rescaled to a time like vector of concurrent form and is a conformal Killing vector. A recent result then shows that the metric is necessarily a generalized Robertson–Walker space-time. In particular we show that a conformally flat [Formula: see text], [Formula: see text], space-time is conformal to the Robertson–Walker space-time.

scholarly journals Colliding scalar pulses in the Einstein-Gauss-Bonnet gravity

2018 ◽  
Vol 168 ◽  
pp. 04014
Author(s):  
Hisaaki Shinkai ◽  
Takashi Torii
Keyword(s):  
Nonlinear Dynamics ◽  
Symmetric Space ◽  
Higher Order ◽  
Space Time ◽  
Large Curvature ◽  
Bonnet Gravity ◽  
Plane Symmetric ◽  
Higher Order Curvature Corrections

We numerically investigated how the nonlinear dynamics depends on the dimensionality and on the higher-order curvature corrections in the form of Gauss-Bonnet (GB) terms, with a model of colliding scalar pulses in plane-symmetric space-time. We observed that a collision of large scalar pulses will produce a large-curvature region, of which the magnitude depends on αGB. The normal corrections (αGB > 0) work for avoiding the appearance of singularity, although it is inevitable.

Induced Quantum Fluctuations in the Spherically Symmetric Space–Time

1997 ◽  
Vol 12 (18) ◽  
pp. 3171-3180 ◽  
Author(s):  
Kamal K. Nandi ◽  
Anwarul Islam ◽  
James Evans
Keyword(s):  
Symmetric Space ◽  
Light Cone ◽  
Quantum Fluctuation ◽  
Quantum Fluctuations ◽  
Dynamical Variable ◽  
Nonrelativistic Limit ◽  
Space Time ◽  
Spherically Symmetric ◽  
Speed Of Light

In the Schwarzschild field due to a mass moving with velocity v → c0, where c0 is the speed of light in vacuum, the source-induced quantum fluctuation in the light cone exhibits consistency with the Aichelburg–Sexl solution while that in the metric dynamical variable does not. At the horizon, none of the fluctuations is proportional to anything finite. However, in the nonrelativistic limit (v → 0), known expressions follow.

Sign in / Sign up

Export Citation Format

Share Document