Results 1 to 10 of about 39,709 (75)

Phantom-Like Behavior in Modified Teleparallel Gravity [PDF]

Advances in High Energy Physics, 4026856, 2019, 2019
The recent data from Planck2018 shows that the equation of state parameter of effective cosmic fluid today is w0 =-1.03. This indicates that it is possible for the universe to be in a phantom dominated era today. While a phantom field is essentially capable to explain this observation, it suffers from some serious problems such as instabilities and ...
arxiv   +1 more source

Phantom maps and rational homotopy [PDF]

arXiv, 2021
We generalize theorems of McGibbon-Roitberg, Iriye, and Meier on the relations between phantom maps and rational homotopy, and apply them to provide new calculational examples of the homotopy sets Ph(X, Y ) of phantom maps and the subsets SPh(X, Y ) of special phantom maps.
arxiv  

Crossing the phantom divide without phantom matter [PDF]

JCAP 0609 (2006) 004, 2006
A class of braneworld models can lead to phantom-like acceleration of the late universe, but without the need for any phantom matter. In the simplest models, the universe contains only cold dark matter and a cosmological constant. We generalize these models by introducing a quintessence field. The new feature in our models is that quintessence leads to
arxiv   +1 more source

Wormholes supported by a phantom energy [PDF]

Phys.Rev. D71 (2005) 043520, 2005
We extend the notion of phantom energy--which is generally accepted for homogeneously distributed matter with $w<-1$ in the universe--on inhomogeneous spherically symmetric spacetime configurations. A spherically symmetric distribution of phantom energy is shown to be able to support the existence of static wormholes.
arxiv   +1 more source

Can universe exit from phantom inflation due to gravitational back reaction? [PDF]

JCAP 0605 (2006) 008, 2006
The effects of the gravitational back reaction of cosmological perturbations are investigated in a phantom inflation model. The effective energy-momentum tensor of the gravitational back reaction of cosmological perturbations whose wavelengths are larger than the Hubble radius is calculated.
arxiv   +1 more source

Phantom Black Holes and Sigma Models [PDF]

Phys.Rev.D83:124001,2011, 2011
We construct static multicenter solutions of phantom Einstein-Maxwell-dilaton theory from null geodesics of the target space, leading to regular black holes without spatial symmetry for certain discrete values of the dilaton coupling constant. We also discuss the three-dimensional gravitating sigma models obtained by reduction of phantom Einstein ...
arxiv   +1 more source

Unifying phantom inflation with late-time acceleration: scalar phantom-non-phantom transition model and generalized holographic dark energy [PDF]

Gen.Rel.Grav.38:1285-1304,2006, 2005
The unifying approach to early-time and late-time universe based on phantom cosmology is proposed. We consider gravity-scalar system which contains usual potential and scalar coupling function in front of kinetic term. As a result, the possibility of phantom-non-phantom transition appears in such a way that universe could have effectively phantom ...
arxiv   +1 more source

Phantom appearance of non-phantom matter [PDF]

Eur.Phys.J. C36 (2004) 523-527, 2003
Two cosmological models with non-phantom matter having the same expansion of the universe as phantom cosmologies are constructed. The first model is characterized by the evolving gravitational "constant" $G$ and a dark energy component with a non-conserved energy-momentum tensor.
arxiv   +1 more source

Transition between phantom and non-phantom phases with time dependent cosmological constant and Cardy-Verlinde formula [PDF]

Europhys.Lett.94:49001,2011, 2011
We investigate the transition phenomenon of the universe between a phantom and a non-phantom phases. Particular attention is devoted to the case in which the cosmological constant depends on time and is proportional to the square of the Hubble parameter. Inhomogeneous equations of state are used and the equation of motion is solved.
arxiv   +1 more source

Phantom energy accretion and primordial black holes evolution in Brans-Dicke theory [PDF]

Eur. Phys. J. C 71, 1837 (2011), 2011
In this work, we study the evolution of primordial black holes within the context of Brans-Dicke theory by considering the presence of a dark energy component with a super-negative equation of state called phantom energy as a background. Besides Hawking evaporation, here we consider two type of accretions - radiation accretion and phantom energy ...
arxiv   +1 more source