Browsing Astronomy and Astrophysics by Title
Now showing items 2140 of 163

Compact conformal manifolds
(20150121) 
A conjectured bound on accidental symmetries
(201201) 
Constraints on the Variation of G from Primordial Nucleosynthesis
We study here the effect of a varying G on the evolution of the early Universe and, in particular, on primordial nucleosynthesis. This variation of G is modelled using the BransDicke theory as well as a more general class ... 
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 nonlinear differential ... 
Cosmology Without Averaging
We construct cosmological models consisting of large numbers of identical, regularly spaced masses. These models do not rely on any averaging procedures, or on the existence of a global FriedmannRobertsonWalker (FRW) ... 
Decaying Gravity
We consider the possibility of energy being exchanged between the scalar and matter fields in scalartensor theories of gravity. Such an exchange provides a new mechanism which can drive variations in the gravitational ... 
Diagnosing shock temperature with NH 3 and H 2 O profiles
(Oxford University Press (OUP), 20161021) 
Dodging the dark matter degeneracy while determining the dynamics of dark energy
(IOP Publishing, 20160501)One of the key issues in cosmology is to establish the nature of dark energy, and to determine whether the equation of state evolves with time. When estimating this from distance measurements there is a degeneracy with the ... 
DYNAMICS OF CO IN AMORPHOUS WATERICE ENVIRONMENTS
(20140120) 
Errors in Estimating Omega_Lambda due to the Fluid Approximation
The matter content of the Universe is strongly inhomogeneous on small scales. Motivated by this fact, we consider a model of the Universe that has regularly spaced discrete masses, rather than a continuous fluid. The optical ... 
Exact cosmological solutions of scaleinvariant gravity theories
We have found new anisotropic vacuum solutions for the scaleinvariant gravity theories which generalise Einstein's general relativity to a theory derived from the Lagrangian $R^{1+\delta}$. These solutions are expanding ... 
Exact Evolution of Discrete Relativistic Cosmological Models
(20130911)We study the effects of inhomogeneities on the evolution of the Universe, by considering a range of cosmological models with discretized matter content. This is done using exact and fully relativistic methods that exploit ... 
Exact Friedmann Solutions in HigherOrder Gravity Theories
We find the general behaviour of homogeneous and isotropic cosmological models in some fourthorder theories of gravity. Explicit, exact, general solutions are given for both empty universes and those filled with a perfect ...