Teleparallel Energy-Momentum Distribution of Lewis-Papapetrou Spacetimes

In this paper, we find the energy-momentum distribution of stationary axisymmetric spacetimes in the context of teleparallel theory by using M$\ddot{o}$ller prescription. The metric under consideration is the generalization of the Weyl metrics called the Lewis-Papapetrou metric. The class of stationary axisymmetric solutions of the Einstein field equations has been studied by Galtsov to include the gravitational effect of an {\it external} source. Such spacetimes are also astrophysically important as they describe the exterior of a body in equilibrium. The energy density turns out to be non-vanishing and well-defined and the momentum becomes constant except along $\theta$-direction. It is interesting to mention that the results reduce to the already available results for the Weyl metrics when we take $\omega=0$.Comment: 13 pages, accepted for publication in Modern Physics Letters

Generalized second law of thermodynamics for a phantom energy accreting BTZ black hole

In this paper, we have studied the accretion of phantom energy on a (2+1)-dimensional stationary Banados-Teitelboim-Zanelli (BTZ) black hole. It has already been shown by Babichev et al that for the accretion of phantom energy onto a Schwarzschild black hole, the mass of black hole would decrease and the rate of change of mass would be dependent on the mass of the black hole. However, in the case of (2+1)-dimensional BTZ black hole, the mass evolution due to phantom accretion is independent of the mass of the black hole and is dependent only on the pressure and density of the phantom energy. We also study the generalized second law of thermodynamics at the event horizon and construct a condition that puts an lower bound on the pressure of the phantom energy.Comment: 4 pages, accepted for publication in Gen. Relativ. Gra

Attractor Solutions in f(T) Cosmology

In this paper, we explore the cosmological implications of interacting dark energy model in a torsion based gravity namely $f(T)$. Assuming dark energy interacts with dark matter and radiation components, we examine the stability of this model by choosing different forms of interaction terms. We consider three different forms of dark energy: cosmological constant, quintessence and phantom energy. We then obtain several attractor solutions for each dark energy model interacting with other components. This model successfully explains the coincidence problem via the interacting dark energy scenario.Comment: 10 pages, 23 figures, version accepted for publication in European Physical Journal C (2012