50 citations · 382 across the 18 of their papers we have counts for
18 papers
Comments on gauge-invariance in cosmology
Karim A. Malik, David R. Matravers
We revisit the gauge issue in cosmological perturbation theory, and highlight its relation to the notion of covariance in general relativity. We also discuss the similarities and d…
Comparing different formulations of non-linear cosmological perturbation theory
Adam J. Christopherson, Karim A. Malik, David R. Matravers +1
We compare and contrast two different metric based formulations of non- linear cosmological perturbation theory: the MW2009 approach in [K. A. Malik and D. Wands, Phys. Rept. 475 (…
Estimating the amount of vorticity generated by cosmological perturbations in the early universe
Adam J. Christopherson, Karim A. Malik, David R. Matravers
We estimate the amount of vorticity generated at second order in cosmological perturbation theory from the coupling between first order energy density and non-adiabatic pressure, o…
Vorticity generation at second order in cosmological perturbation theory
Adam J. Christopherson, Karim A. Malik, David R. Matravers
We show that at second order in cosmological perturbation theory vorticity generation is sourced by entropy gradients. This is an extension of Crocco's theorem to a cosmological se…
A Concise Introduction to Perturbation Theory in Cosmology
Karim A. Malik, David R. Matravers
We give a concise, self-contained introduction to perturbation theory in cosmology at linear and second order, striking a balance between mathematical rigour and usability. In part…
Braneworld cosmological models with anisotropy
Antonio Campos, Roy Maartens, David Matravers +1
For a cosmological Randall-Sundrum braneworld with anisotropy, i.e., of Bianchi type, the modified Einstein equations on the brane include components of the five-dimensional Weyl t…