scholarly journals Rotating wormhole solutions with a complex phantom scalar field

2019 ◽  
Vol 100 (4) ◽  
Author(s):  
Xiao Yan Chew ◽  
Burkhard Kleihaus ◽  
Jutta Kunz ◽  
Vladimir Dzhunushaliev ◽  
Vladimir Folomeev
Keyword(s):  
Scalar Field ◽  
Phantom Scalar ◽  
Phantom Scalar Field

scholarly journals Comment on “A study of phantom scalar field cosmology using Lie and Noether symmetries”

2016 ◽  
Vol 25 (14) ◽  
pp. 1675001
Author(s):  
Andronikos Paliathanasis ◽  
Spyros Basilakos ◽  
Michael Tsamparlis
Keyword(s):  
Dynamical System ◽  
Scalar Field ◽  
Coordinate System ◽  
Coordinate Transformation ◽  
Noether Symmetries ◽  
Phantom Scalar ◽  
Scalar Field Cosmology ◽  
Phantom Scalar Field

We show that the recent results of [S. Dutta and S. Chakraborty, Int. J. Mod. Phys. D 25 (2016) 1650051] on the application of Lie/Noether symmetries in scalar field cosmology are well-known in the literature while the problem could have been solved easily under a coordinate transformation. That follows from the property, that the admitted group of invariant transformations of dynamical system is independent on the coordinate system.

scholarly journals Null and Timelike Geodesics near the Throats of Phantom Scalar Field Wormholes

Universe ◽  
2020 ◽  
Vol 6 (10) ◽  
pp. 183
Author(s):  
Ivan Potashov ◽  
Julia Tchemarina ◽  
Alexander Tsirulev
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Circular Orbit ◽  
Realistic Model ◽  
Test Particles ◽  
Stable Circular Orbit ◽  
Phantom Scalar ◽  
Metric Function ◽  
Bound Orbits ◽  
Phantom Scalar Field

We study geodesic motion near the throats of asymptotically flat, static, spherically symmetric traversable wormholes supported by a self-gravitating minimally coupled phantom scalar field with an arbitrary self-interaction potential. We assume that any such wormhole possesses the reflection symmetry with respect to the throat, and consider only its observable “right half”. It turns out that the main features of bound orbits and photon trajectories close to the throats of such wormholes are very different from those near the horizons of black holes. We distinguish between wormholes of two types, the first and second ones, depending on whether the redshift metric function has a minimum or maximum at the throat. First, it turns out that orbits located near the centre of a wormhole of any type exhibit retrograde precession, that is, the angle of pericentre precession is negative. Second, in the case of high accretion activity, wormholes of the first type have the innermost stable circular orbit at the throat while those of the second type have the resting-state stable circular orbit in which test particles are at rest at all times. In our study, we have in mind the possibility that the strongly gravitating objects in the centres of galaxies are wormholes, which can be regarded as an alternative to black holes, and the scalar field can be regarded as a realistic model of dark matter surrounding galactic centres. In this connection, we discuss qualitatively some observational aspects of results obtained in this article.

scholarly journals Unified universe history through phantom extended Chaplygin gas

2016 ◽  
Vol 94 (7) ◽  
pp. 659-670 ◽  
Author(s):  
B. Pourhassan
Keyword(s):  
Scalar Field ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Late Time ◽  
Two Component ◽  
Equation Of State Parameter ◽  
Phantom Scalar ◽  
The Universe ◽  
Phantom Scalar Field ◽  
Universe Evolution

The universe evolution from inflation to late-time acceleration is investigated in a unified way, using a two-component fluid constituted from extended Chaplygin gas alongside a phantom scalar field. We extract solutions for the various cosmological eras, focusing on the behavior of the scale factor, the various density parameters and the equation-of-state parameter. Furthermore, we extract and discuss bouncing solutions. Finally, we examine the perturbations of the model, ensuring their stability and extracting the predictions for the tensor-to-scalar ratio.

Sign in / Sign up

Export Citation Format

Share Document