scholarly journals Energy conditions in F(T,Θ) gravity and compatibility with a stable de Sitter solution

2014 ◽  
Vol 728 ◽  
pp. 554-561 ◽  
Author(s):  
Faeze Kiani ◽  
Kourosh Nozari
Keyword(s):  
Energy Conditions ◽  
De Sitter ◽  
Sitter Solution

scholarly journals Energy conditions in non-local gravity

2019 ◽  
Vol 16 (10) ◽  
pp. 1950149 ◽  
Author(s):  
M. Ilyas
Keyword(s):  
Power Law ◽  
Arbitrary Function ◽  
Energy Conditions ◽  
De Sitter ◽  
Sitter Solution ◽  
Local Gravity ◽  
Non Local

We investigate the different energy conditions in non-local gravity, which is obtained by adding an arbitrary function of d’Alembertian operator, [Formula: see text], to the Hilbert–Einstein action. We analyze the validity of four different energy conditions and illustrate the different constraints over parameters of the power-law solution as well as de Sitter solution.

scholarly journals Traversable wormholes in Einsteinian cubic gravity

2019 ◽  
Vol 35 (06) ◽  
pp. 2050017 ◽  
Author(s):  
Mohammad Reza Mehdizadeh ◽  
Amir Hadi Ziaie
Keyword(s):  
Equation Of State ◽  
Gravitational Lensing ◽  
Energy Condition ◽  
Higher Order ◽  
Energy Conditions ◽  
Geodesic Motion ◽  
De Sitter ◽  
Asymptotically Flat ◽  
Traversable Wormholes ◽  
Standard Energy

In this work, we investigate wormhole configurations described by a constant redshift function in Einstein-Cubic gravity ( ECG ). We derive analytical wormhole geometries by assuming a particular equation of state ( EoS ) and investigate the possibility that these solutions satisfy the standard energy conditions. We introduce exact asymptotically flat and anti-de Sitter (AdS) spacetimes that admit traversable wormholes. These solutions are obtained by imposing suitable values for the parameters of the theory so that the resulted geometries satisfy the weak energy condition ( WEC ) in the vicinity of the throat, due to the presence of higher-order curvature terms. Moreover, we find that AdS solutions satisfy the WEC throughout the spacetime. A description of the geodesic motion of time-like and null particles is presented for the obtained wormhole solutions. Also, using gravitational lensing effects, observational features of the wormhole structure are discussed.

scholarly journals PHANTOM AND QUANTUM MATTER IN AN ANTI DE SITTER UNIVERSE

2004 ◽  
Vol 19 (01) ◽  
pp. 29-36 ◽  
Author(s):  
EMILIO ElIZALDE ◽  
JOHN QUIROGA HURTADO
Keyword(s):  
Perfect Fluid ◽  
Quantum Effects ◽  
Energy Conditions ◽  
De Sitter ◽  
Quantum Matter ◽  
Trace Anomaly ◽  
Sitter Universe ◽  
De Sitter Universe ◽  
Phantom Matter

We consider an anti de Sitter universe filled by quantum CFT with classical phantom matter and perfect fluid. The model represents the combination of a trace-anomaly annihilated and a phantom driven anti de Sitter universes. The influence exerted by the quantum effects and phantom matter on the AdS space is discussed. Different energy conditions in this type of universe are investigated and compared with those for the corresponding model in a de Sitter universe.

scholarly journals DUALITY AND SELF-DUAL TRIPLET SOLUTIONS IN EUCLIDEAN GRAVITY

1996 ◽  
Vol 11 (34) ◽  
pp. 2669-2679
Author(s):  
SWAPNA MAHAPATRA
Keyword(s):  
String Theory ◽  
The Self ◽  
Target Space ◽  
De Sitter ◽  
Gravitational Instanton ◽  
Duality Symmetry ◽  
Sitter Solution

Starting from the self-dual “triplet” of gravitational instanton solutions in Euclidean gravity, we obtain the corresponding instanton solutions in string theory by making use of the target space duality symmetry. We show that these dual triplet solutions can be obtained from the general dual Taub-NUT de Sitter solution through some limiting procedure as in the Euclidean gravity case. The dual gravitational instanton solutions obtained here are self-dual for some cases, with respect to certain isometries, but not always.

scholarly journals CROSSING THE PHANTOM DIVIDE WITH k-ESSENCE IN BRANEWORLDS

2010 ◽  
Vol 25 (29) ◽  
pp. 2469-2481 ◽  
Author(s):  
LUIS P. CHIMENTO ◽  
MÓNICA FORTE ◽  
MARTÍN G. RICHARTE
Keyword(s):  
Equation Of State ◽  
High Energy ◽  
Chaplygin Gas ◽  
Energy Conditions ◽  
De Sitter ◽  
Effective Equation ◽  
Phantom Divide ◽  
Energy Regime ◽  
High Energy Regime ◽  
Stable Stage

We study a flat three-brane in the presence of a linear k field with nonzero cosmological constant Λ4. In this model the crossing of the phantom divide (PD) occurs when the k-essence energy density becomes negative. We show that in the high energy regime the effective equation of state has a resemblance of a modified Chaplygin gas while in the low energy regime it becomes linear. We find a scale factor that begins from a singularity and evolves to a de Sitter stable stage while other solutions have a super-accelerated regime and end with a big rip. We use the energy conditions to show when the effective equation of state of the brane-universe crosses the PD.

scholarly journals TACHYON FIELDS WITH EFFECTS OF QUANTUM MATTER IN AN ANTI-DE SITTER UNIVERSE

2005 ◽  
Vol 14 (08) ◽  
pp. 1439-1449 ◽  
Author(s):  
EMILIO ELIZALDE ◽  
JOHN QUIROGA HURTADO
Keyword(s):  
Perfect Fluid ◽  
Quantum Effects ◽  
Accelerated Expansion ◽  
Energy Conditions ◽  
De Sitter ◽  
Quantum Matter ◽  
Trace Anomaly ◽  
Sitter Universe ◽  
Proposed Model ◽  
De Sitter Universe

We consider an Anti-de Sitter universe filled by quantum conformal matter with the contribution from the usual tachyon and a perfect fluid. The model represents the combination of a trace-anomaly annihilated and a tachyon driven Anti-de Sitter universe. The influence exerted by the quantum effects and by the tachyon on the AdS space is studied. The radius corresponding to this universe is calculated and the effect of the tachyon potential is discussed, in particular, concerning the possibility to get an accelerated scale factor for the proposed model (which yields an accelerated expansion of the AdS type of universe). Fulfillment of the cosmological energy conditions in the model is also investigated.

scholarly journals New asymptotic Anti-de Sitter solution with a timelike extra dimension in 5D relativity

2017 ◽  
Vol 382 ◽  
pp. 112-126
Author(s):  
Molin Liu ◽  
Yingying Shi ◽  
Zonghua Zhao ◽  
Yu Han
Keyword(s):  
Extra Dimension ◽  
De Sitter ◽  
Sitter Solution

scholarly journals Schwarzschild-de Sitter and Anti-de Sitter Thin-Shell Wormholes and Their Stability

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
M. Sharif ◽  
Saadia Mumtaz
Keyword(s):  
Thin Shell ◽  
Chaplygin Gas ◽  
Exotic Matter ◽  
Energy Conditions ◽  
Energy Tensor ◽  
De Sitter ◽  
Stress Energy ◽  
Linear Perturbations ◽  
Unstable Solutions ◽  
Thin Shell Wormholes

This paper is devoted to construct Schwarzschild-de Sitter and anti-de Sitter thin-shell wormholes by employing Visser’s cut and paste technique. The Darmois-Israel formalism is adopted to formulate the surface stresses of the shell. We analyze null and weak energy conditions as well as attractive and repulsive characteristics of thin-shell wormholes. We also explore stable and unstable solutions against linear perturbations by taking two different Chaplygin gas models for exotic matter. It is concluded that the stress-energy tensor components violate the null and weak energy conditions indicating the existence of exotic matter at the wormhole throat. Finally, we find unstable and stable configurations for the constructed thin-shell wormholes.

scholarly journals ENERGY DISTRIBUTION OF BLACK PLANE SOLUTIONS

2006 ◽  
Vol 21 (06) ◽  
pp. 495-502 ◽  
Author(s):  
PAUL HALPERN
Keyword(s):  
Energy Distribution ◽  
Cosmological Constant ◽  
Electric Charge ◽  
Maxwell Equations ◽  
De Sitter ◽  
Plane Symmetric ◽  
Sitter Solution ◽  
Static Plane ◽  
Momentum Complex ◽  
Black Plane

We use the Einstein energy–momentum complex to calculate the energy distribution of static plane-symmetric solutions of the Einstein–Maxwell equations in 3+1 dimensions with asymptotic anti-de Sitter behavior. This solution is expressed in terms of three parameters: the mass, electric charge and cosmological constant. We compare the energy distribution to that of the Reissner–Nordström–anti-de Sitter solution, pointing to qualitative differences between the models. Finally, we examine these results within the context of the Cooperstock hypothesis.

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