Browsing Astronomy and Astrophysics by Subject "astro-ph.CO"
Now showing items 1-16 of 16
-
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 Friedmann-Robertson-Walker (FRW) ... -
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 ... -
FRW cosmology in Milgrom's bimetric theory of gravity
We consider spatially homogeneous and isotropic Friedmann-Robertson-Walker (FRW) solutions of Milgrom's recently proposed class of bimetric theories of gravity. These theories have two different regimes, corresponding to ... -
Hubble Diagram Dispersion From Large-Scale Structure
We consider the effects of large structures in the Universe on the Hubble diagram. This problem is treated non-linearly by considering a Swiss Cheese model of the Universe in which under-dense voids are represented as ... -
An Improved Treatment of Optics in the Lindquist-Wheeler Models
We consider the optical properties of Lindquist-Wheeler (LW) models of the Universe. These models consist of lattices constructed from regularly arranged discrete masses. They are akin to the Wigner-Seitz construction of ... -
The isotropic blackbody CMB as evidence for a homogeneous universe
(American Physical Society, 2012-08-01)The question of whether the Universe is spatially homogeneous and isotropic on the largest scales is of fundamental importance to cosmology, but has not yet been answered decisively. Surprisingly, neither an isotropic ... -
The Method of Images in Cosmology
We apply the method of images to the exact initial data for cosmological models that contain a number of regularly arranged discrete masses. This allows us to join cosmological regions together by throats, and to construct ... -
Modified Gravity and Cosmology
In this review we present a thoroughly comprehensive survey of recent work on modified theories of gravity and their cosmological consequences. Amongst other things, we cover General Relativity, Scalar-Tensor, Einstein-Aether, ... -
Observational Constraints on the Completeness of Space near Astrophysical Objects
We consider the observational effects of a deficit angle, w, in the topology of the solar system and in the 'double pulsar' system PSR J0737-3039A/B. Using observations of the perihelion precession of Mercury, and the ... -
Observational Cosmology in Macroscopic Gravity
We discuss the construction of cosmological models within the framework of Macroscopic Gravity (MG), which is a theory that models the effects of averaging the geometry of space-time on large scales. We find new exact ... -
On the Emergence of Accelerating Cosmic Expansion in f(R) Theories of Gravity
We consider cosmological modelling in $f(R)$ theories of gravity, using both top-down and bottom-up constructions. The top-down models are based on Robertson-Walker geometries, and the bottom-up constructions are built by ... -
The Parameterised Post-Newtonian Limit of Bimetric Theories of Gravity
We consider the post-Newtonian limit of a general class of bimetric theories of gravity, in which both metrics are dynamical. The established parameterised post-Newtonian approach is followed as closely as possible, although ... -
Perturbation Theory in Lemaitre-Tolman-Bondi Cosmology
The Lemaitre-Tolman-Bondi solution has received much attention as a possible alternative to Dark Energy, as it is able to account for the apparent acceleration of the Universe without any exotic matter content. However, ... -
Piecewise Silence in Discrete Cosmological Models
We consider a family of cosmological models in which all mass is confined to a regular lattice of identical black holes. By exploiting the reflection symmetry about planes that bisect these lattices into identical halves, ... -
PyTransport: A Python package for the calculation of inflationary correlation functions
(2016-09-05)PyTransport constitutes a straightforward code written in C++ together with Python scripts which automatically edit, compile and run the C++ code as a Python module. It has been written for Unix-like systems (OS X and ... -
What the small angle CMB really tells us about the curvature of the Universe
It is well known that observations of the cosmic microwave background (CMB) are highly sensitive to the spatial curvature of the Universe, k. Here we find that what is in fact being tightly constrained by small angle ...
