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Non-resonant nonlinear coupling of magnetohydrodynamic waves in inhomogeneous media
A new mechanism for the enhanced generation of compressible fluctuations by Alfven waves is presented. A strongly nonlinear regime of Alfven wave phase-mixing is numerically simulated in a one-dimensionally inhomogeneous ...
A Simple Model for Pulse Profiles from Precessing Pulsars, with Special Application to Relativistic Binary PSR B1913+16
(American Astronomical Society, 2008-05-31)
We study the observable pulse profiles that can be generated from precessing pulsars. A novel coordinate system is defined to aid visualization of the observing geometry. Using this system we explore the different families ...
Properties of Black Hole Radiation From Tunnelling
We consider the space-time associated with the evaporation of a black hole by quantum mechanical tunnelling events. It is shown that the surface through which tunnelling occurs is distinct from the global event horizon, ...
Decaying Gravity
We consider the possibility of energy being exchanged between the scalar and matter fields in scalar-tensor theories of gravity. Such an exchange provides a new mechanism which can drive variations in the gravitational ...
Further Exact Cosmological Solutions to Higher-Order Gravity Theories
We investigate the effect of deviations from general relativity on approach to the initial singularity by finding exact cosmological solutions to a wide class of fourth-order gravity theories. We present new anisotropic ...
The Ups and Downs of Cyclic Universes
We investigate homogeneous and isotropic oscillating cosmologies with multiple fluid components. Transfer of energy between these fluids is included in order to model the effects of non-equilibrium behavior on closed ...
Cosmologies with Energy Exchange
We provide a simple mathematical description of the exchange of energy between two fluids in an expanding Friedmann universe with zero spatial curvature. The evolution can be reduced to a single non-linear differential ...
The Existence of Godel, Einstein and de Sitter Universes
We determine the general conditions for the existence of Godel, Einstein static, and de Sitter universes in gravity theories derived from a Lagrangian that is an arbitrary function of the scalar curvature and Ricci and ...
Exact cosmological solutions of scale-invariant gravity theories
We have found new anisotropic vacuum solutions for the scale-invariant gravity theories which generalise Einstein's general relativity to a theory derived from the Lagrangian $R^{1+\delta}$. These solutions are expanding ...
Volume Weighted Measures of Eternal Inflation in the Bousso-Polchinski Landscape
We consider the cosmological dynamics associated with volume weighted measures of eternal inflation, in the Bousso-Polchinski model of the string theory landscape. We find that this measure predicts that observers are most ...