A possible candidate for the present accelerated expansion of the Universe is “phantom energy”, which possesses an equation of state of the form ω ≡ p/ρ < −1, consequently violating the null energy condition. As this is the fundamental ingredient to sustain traversable wormholes, this cosmic fluid presents us with a natural scenario for the existence of these exotic geometries. In this context,...

Cosmology of self-interacting three-forms is investigated. The minimally coupled canonical theory can naturally generate a variety of isotropic background dynamics, including scaling, possibly transient acceleration and phantom crossing. An intuitive picture of the cosmological dynamics is presented employing an effective potential. Numerical solutions and analytical approximations are provided...

(2012) Mapping the invisible hand: a body model of a phantom limb.

In this note, we attack a question posed ten years ago by Tsukiyama about the injectivity of the socalled Forgetable map. We show that we can insert the Forgetable map in an exact sequence and that the problem can be reduced to the computation of the sequence which turns out unexpectedly to be related to the phantom map problem and the famous Halperin conjecture in rational homotopy theory.

Equation of state parameter plays a significant role for guessing the real nature of dark energy. In the present paper polytropic equation of state p = ωρn is chosen for some of the kinematical Λ-models viz., Λ ∼ (ȧ/a), Λ ∼ ä/a and Λ ∼ ρ. Although in dust cases (ω = 0) closed form solutions show no dependency on the polytropic index n, but in non-dust situations some new possibilities are opene...

Based on dilatonic dark energy model, we consider two cases: dilaton field with positive kinetic energy(coupled quintessence) and with negative kinetic energy(phantom). In the two cases, we investigate the existence of attractor solutions which correspond to an equation of state parameter ω = −1 and a cosmic density parameter Ωσ = 1. We find that the coupled term between matter and dilaton can’...

Here, RS-II model of brane-gravity is considered for phantom universe using non-linear equation of state. Phantom fluid is known to violate the weak energy condition. In this paper, it is found that this characteristic of phantom energy is affected drastically by the negative brane-tension λ of the RS-II model. It is interesting to see that upto a certain value of energy density ρ satisfying ρ/...

We consider fluid perturbations close to the ‘‘phantom divide’’ characterized by p and discuss the conditions under which divergencies in the perturbations can be avoided. We find that the behavior of the perturbations depends crucially on the prescription for the pressure perturbation p. The pressure perturbation is usually defined using the dark energy rest-frame, but we show that this frame ...

enhancement after contrast injection, with 4 lesions present, 10 min after contrast injection.(b) Image obtained by subtracting non-enhanced image initial image from the final image at 10 min improves visualization of simulated lesions. Arrow indicates lesion for which subsequent error calculation has been performed (see below) (c) signal intensity vs. time (SIT) curve curves associated with le...