695 citations · 7k across the 122 of their papers we have counts for
18 papers · 1 filter
The cosmological background of vector modes
Teresa Hui-Ching Lu, Kishore Ananda, Chris Clarkson +1
We investigate the spectrum of vector modes today which is generated at second order by density perturbations. The vector mode background that is generated by structure formation i…
Model independent constraints on the cosmological expansion rate
Edvard Mortsell, Chris Clarkson
We investigate what current cosmological data tells us about the cosmological expansion rate in a model independent way. Specifically, we study if the expansion was decelerating at…
A litmus test for Lambda
Caroline Zunckel, Chris Clarkson
The critical issue in cosmology today lies in determining if the cosmological constant is the underlying ingredient of dark energy. Our profound lack of understanding of the physic…
Non-parametric Dark Energy Degeneracies
Renée Hlozek, Marina Cortês, Chris Clarkson +1
We study the degeneracies between dark energy dynamics, dark matter and curvature using a non-parametric and non-perturbative approach. This allows us to examine the knock-on bias…
Time drift of cosmological redshifts as a test of the Copernican principle
Jean-Philippe Uzan, Chris Clarkson, George F. R. Ellis
We present the time drift of the cosmological redshift in a general spherically symmetric spacetime. We demonstrate that its observation would allow us to test the Copernican princ…
A general test of the Copernican Principle
Chris Clarkson, Bruce A. Bassett, Teresa Hui-Ching Lu
The recent discovery of apparent cosmic acceleration has highlighted the depth of our ignorance of the fundamental properties of nature. It is commonly assumed that the explanation…
Vector modes generated by primordial density fluctuations
Teresa Hui-Ching Lu, Kishore Ananda, Chris Clarkson
While vector modes are usually ignored in cosmology since they are not produced during inflation they are inevitably produced from the interaction of density fluctuations of differ…
Dynamical Dark Energy or Simply Cosmic Curvature?
Chris Clarkson, Marina Cortes, Bruce A. Bassett
We show that the assumption of a flat universe induces critically large errors in reconstructing the dark energy equation of state at z>~0.9 even if the true cosmic curvature is ve…
A gravitational wave window on extra dimensions
Chris Clarkson, Sanjeev S. Seahra
We report on the possibility of detecting a submillimetre-sized extra dimension by observing gravitational waves (GWs) emitted by pointlike objects orbiting a braneworld black hole…
Gravity-wave detectors as probes of extra dimensions
Chris Clarkson, Roy Maartens
If string theory is correct, then our observable Universe may be a 3-dimensional "brane" embedded in a higher-dimensional spacetime. This theoretical scenario should be tested via…
The general relativistic MHD dynamo equation
Mattias Marklund, Chris Clarkson
The magnetohydrodynamic dynamo equation is derived within general relativity, using the covariant 1+3 approach, for a plasma with finite electric conductivity. This formalism allow…
Cosmological density fluctuations and gravity waves: A covariant approach to gauge-invariant non-linear perturbation theory
Chris Clarkson
We present a new approach to gauge-invariant cosmological perturbations at second order, which is also covariant. We examine two cases in particular for a dust Friedman-Lemaitre-Ro…
The electromagnetic signature of black hole ringdown
C. Clarkson, M. Marklund, G. Betschart +1
We investigate generation of electromagnetic radiation by gravitational waves interacting with a strong magnetic field in the vicinity of a vibrating Schwarzschild black hole. Such…
CMB limits on large-scale magnetic fields in an inhomogeneous universe
C. A. Clarkson, A. A. Coley, R. Maartens +1
We use the cosmic microwave background temperature anisotropy to place limits on large-scale magnetic fields in an inhomogeneous (perturbed Friedmann) universe. If no assumptions a…
Qualitative Properties of Magnetic Fields in Scalar Field Cosmology
C. A. Clarkson, A. A. Coley, S. D. Quinlan
We study the qualitative properties of the class of spatially homogeneous Bianchi VI_o cosmological models containing a perfect fluid with a linear equation of state, a scalar fiel…
Magnetic Fields and the Cosmic Microwave Background
C. A. Clarkson, A. A. Coley
Observations of the high degree of isotropy of the cosmic microwave background are commonly believed to indicate that the Universe is `almost' Friedmann-Lemaitre-Robertson-Walker (…
On the Observational Characteristics of Inhomogeneous Cosmologies: Undermining the Cosmological Principle
Chris A. Clarkson
This thesis concerns the compatibility of inhomogeneous cosmologies with our present understanding of the universe. It is a problem of some interest to find the class of all relati…
Undermining the Cosmological Principle: Almost Isotropic Observations in Inhomogeneous Cosmologies
R. K. Barrett, C. A. Clarkson
We challenge the widely held belief that the cosmological principle is an obvious consequence of the observed isotropy of the cosmic microwave background radiation, combined with t…