695 citations · 7k across the 122 of their papers we have counts for
22 papers · 1 filter
Multi-Scale Perturbation Theory II: Solutions and Leading-Order Bispectrum in the CDM Universe
Christopher S. Gallagher, Timothy Clifton, Chris Clarkson
Two-parameter perturbation theory (2PPT) is a framework designed to include the relativistic gravitational effects of small-scale nonlinear structures on the large-scale properties…
Multi-Scale Perturbation Theory I: Methodology and Leading-Order Bispectrum Corrections in the Matter-Dominated Era
Christopher Gallagher, Timothy Clifton, Chris Clarkson
Two-parameter perturbation theory is a scheme tailor-made to consistently include nonlinear density contrasts on small scales (), whilst retaining a traditiona…
Recursion relations for gravitational lensing
Ben David Normann, Chris Clarkson
The weak gravitational lensing formalism can be extended to the strong lensing regime by integrating a nonlinear version of the geodesic deviation equation. The resulting "roulette…
Roulettes: A weak lensing formalism for strong lensing - II. Derivation and analysis
Chris Clarkson
We present a new extension of the weak lensing formalism capable of describing strongly lensed images. This paper accompanies Paper I, arXiv:1603.04698 where we provided a condense…
Cosmological evolution of the gravitational entropy of the large-scale structure
Giovanni Marozzi, Jean-Philippe Uzan, Obinna Umeh +1
We consider the entropy associated with the large-scale structure of the Universe in the linear regime, where the Universe can be described by a perturbed Friedmann-Lemaître spacet…
Non-linear relativistic contributions to the cosmological weak-lensing convergence
Sambatra Andrianomena, Chris Clarkson, Prina Patel +2
Relativistic contributions to the dynamics of structure formation come in a variety of forms, and can potentially give corrections to the standard picture on typical scales of 100…
The isotropic blackbody CMB as evidence for a homogeneous universe
Timothy Clifton, Chris Clarkson, Philip Bull
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 decisivel…
Locally extracting scalar, vector and tensor modes in cosmological perturbation theory
Chris Clarkson, Bob Osano
Cosmological perturbation theory relies on the decomposition of perturbations into so-called scalar, vector and tensor modes. This decomposition is non-local and depends on unknowa…
Gravitational Lensing in Spherically Symmetric Spacetimes
Bonita de Swardt, Peter K. S. Dunsby, Chris Clarkson
We present a framework for studying gravitational lensing in spherically symmetric spacetimes using 1+1+2 covariant methods. A general formula for the deflection angle is derived a…
Gravitational waves in the black string braneworld
Sanjeev S. Seahra, Chris Clarkson
We study gravitational waves in the black string Randall-Sundrum braneworld. We present a reasonably self-contained and complete derivation of the equations governing the evolution…
A covariant approach for perturbations of rotationally symmetric spacetimes
Chris Clarkson
We present a covariant decomposition of Einstein's Field Equations which is particularly suitable for perturbations of spherically symmetric -- and general locally rotationally sym…
Gravitational waves generated by second order effects during inflation
Bob Osano, Cyril Pitrou, Peter Dunsby +2
The generation of gravitational waves during inflation due to the non-linear coupling of scalar and tensor modes is discussed. Two methods describing gravitational wave perturbatio…
The cosmological gravitational wave background from primordial density perturbations
Kishore N. Ananda, Chris Clarkson, David Wands
We discuss the gravitational wave background generated by primordial density perturbations evolving during the radiation era. At second-order in a perturbative expansion, density f…
Braneworld resonances
Chris Clarkson, Sanjeev S. Seahra
We investigate in detail gravitational waves in an Schwarzschild-anti-de Sitter bulk spacetime surrounded by an Einstein static brane with generic matter content. Such a model prov…
Delocalization of brane gravity by a bulk black hole
Sanjeev S. Seahra, Chris Clarkson, Roy Maartens
We investigate the analogue of the Randall-Sundrum brane-world in the case when the bulk contains a black hole. Instead of the static vacuum Minkowski brane of the RS model, we hav…
Detecting extra dimensions with gravity wave spectroscopy: the black string brane-world
Sanjeev S. Seahra, Chris Clarkson, Roy Maartens
Using the black string between two branes as a model of a brane-world black hole, we compute the gravity wave perturbations and identify the features arising from the additional po…
Scalar field and electromagnetic perturbations on Locally Rotationally Symmetric spacetimes
Gerold Betschart, Chris A. Clarkson
We study scalar field and electromagnetic perturbations on Locally Rotationally Symmetric (LRS) class II spacetimes, exploiting a recently developed covariant and gauge-invariant p…
Inhomogeneous cosmologies, the Copernican principle and the cosmic microwave background: More on the EGS theorem
C. A. Clarkson, A. A. Coley, E. S. D. O'Neill +2
We discuss inhomogeneous cosmological models which satisfy the Copernican principle. We construct some inhomogeneous cosmological models starting from the ansatz that the all the o…
Covariant Perturbations of Schwarzschild Black Holes
Chris A. Clarkson, Richard K. Barrett
We present a new covariant and gauge-invariant perturbation formalism for dealing with spacetimes having spherical symmetry (or some preferred spatial direction) in the background,…
On Scaling Solutions with a Dissipative Fluid
J. Ibanez, C. A. Clarkson, A. A. Coley
We study the asymptotic behaviour of scaling solutions with a dissipative fluid and we show that, contrary to recent claims, the existence of stable accelerating attractor solution…
The Cosmic Microwave Background and Scalar-Tensor Theories of Gravity
C. A. Clarkson, A. A. Coley, E. S. D. O'Neill
We show that if all observers see an isotropic cosmic microwave background in an expanding geodesic perfect fluid spacetime within a scalar-tensor theory of gravity, then that spac…
Does the Isotropy of the CMB Imply a Homogeneous Universe? Some Generalised EGS Theorems
Chris Clarkson, Richard Barrett
We demonstrate that the high isotropy of the Cosmic Microwave Background (CMB), combined with the Copernican principle, is not sufficient to prove homogeneity of the universe -- in…