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The formulation of quasilocal conformal Killing horizons (CKH) is extended to include rotation. This necessitates that the horizon be foliated by 2-spheres which may be distorted. Matter degrees of freedom which fall through the horizon are represented by a real scalar field. We show that these rotating CKHs also admit a first law in differential form. [ABSTRACT FROM AUTHOR]

We examine quintessence models for dark energy in which the scalar field ɸ evolves near the vicinity of a local maximum or minimum in the potential V(ɸ), so that V(ɸ) can be approximated by a quadratic function of ɸ with no linear term. We generalize previous studies of this type by allowing the initial value of dɸ/dt to be nonzero. We derive an analytic approximation for w(a) and show that it is in excellent agreement with numerical simulations for a variety of scalar field potentials having local minima or maxima. We derive an upper bound on the present-day value of w as a function of the other model parameters and present representative limits on these models from observational data. This work represents a final generalization of previous studies using linear or quadratic approximations for V(ɸ). [ABSTRACT FROM AUTHOR]

If vector type perturbations are present in the primordial plasma before recombination, the generation of magnetic fields is known to be inevitable through the Harrison mechanism. In the context of the standard cosmological perturbation theory, nonlinear couplings of first-order scalar perturbations create second-order vector perturbations, which generate magnetic fields. Here we reinvestigate the generation of magnetic fields at second-order in cosmological perturbations on the basis of our previous study, and extend it by newly taking into account the time evolution of purely second-order vector perturbations with a newly developed second-order Boltzmann code. We confirm that the amplitude of magnetic fields from the product-terms of the first-order scalar modes is consistent with the result in our previous study. However, we find, both numerically and analytically, that the magnetic fields from the purely second-order vector perturbations partially cancel out the magnetic fields from one of the product-terms of the first-order scalar modes, in the tight coupling regime in the radiation dominated era. Therefore, the amplitude of the magnetic fields on small scales, k≳10 hMpc-1, is smaller than the previous estimates. The amplitude of the generated magnetic fields at cosmological recombination is about Brec = 5.0×10-24 Gauss on k = 5.0×10-1 hMpc-1. Finally, we discuss the reason for the discrepancies that exist in estimates of the amplitude of magnetic fields among other authors. [ABSTRACT FROM AUTHOR]

We consider a model of the early Universe which consists of two scalar fields: the inflaton and a second field which drives the stabilization of the Planck mass (or gravitational constant). We show that the nonminimal coupling of this second field to the Ricci scalar sources a nonadiabatic pressure perturbation. By performing a fully numerical calculation, we find, in turn, that this boosts the amplitude of the primordial power spectrum after inflation. [ABSTRACT FROM AUTHOR]

We present rotating wormhole solutions in general relativity, which are supported by a phantom scalar field. These solutions evolve from the static Ellis wormhole, when the throat is set into rotation. As the rotational velocity increases, the throat deforms until, at a maximal value of the rotational velocity, an extremal Kerr solution is encountered. The rotating wormholes attain a finite mass and quadrupole moment. They exhibit ergospheres and possess bound orbits. [ABSTRACT FROM AUTHOR]