Power-law cosmic expansion in f(R) gravity models (2009)
Goheer, Naureen, Larena, Julien, Dunsby, Peter K. S.
We show that within the class of f(R) gravity theories, FLRW power-law perfect fluid solutions only exist for R^n gravity. This significantly restricts the set of exact cosmological solutions which...
On the co-existence of matter dominated and accelerating solutions in f(G)-gravity (2009)
Goheer, Naureen, Goswami, Rituparno, Dunsby, Peter K. S., Ananda, Kishore
Working within the theory of modified Gauss-Bonnet gravity, we show that FLRW--like power--law solutions only exist for a very special class of f(G)theories. Furthermore, we point out that any...
Dynamics of f(R)-cosmologies containing Einstein static models (2008)
Goheer, Naureen, Goswami, Rituparno, Dunsby, Peter K. S.
We study the dynamics of homogeneous isotropic FRW cosmologies with positive spatial curvature in $f(R)$-gravity, paying special attention to the existence of Einstein static models and only study...
Goswami, Rituparno, Goheer, Naureen, Dunsby, Peter K. S.
We investigate whether or not an Einstein Static universe is a solution to the cosmological equations in $f(R)$ gravity. It is found that only one class of $f(R)$ theories admits an Einstein Static...
Dynamical systems analysis of anisotropic cosmologies in $R^n$-gravity (2007)
Goheer, Naureen, Leach, Jannie A., Dunsby, Peter K. S.
In this paper we study the dynamics of {\it orthogonal spatially homogeneous} Bianchi cosmologies in $R^n$-gravity. We construct a compact state space by dividing the state space into different...
Compactifying the state space for alternative theories of gravity (2007)
Goheer, Naureen, Leach, Jannie A., Dunsby, Peter K. S.
In this paper we address important issues surrounding the choice of variables when performing a dynamical systems analysis of alternative theories of gravity. We discuss the advantages and...
Large-scale perturbations on the brane and the isotropy of the cosmological singularity (2004)
Goheer, Naureen, Dunsby, Peter K. S., Coley, Alan, Bruni, Marco
We present the complete set of propagation and constraint equations for the kinematic and non-local first order quantities which describe general linear inhomogeneous and anisotropic perturbations of...
Are braneworlds born isotropic? (2003)
Dunsby, Peter K. S., Goheer, Naureen, Bruni, Marco, Coley, Alan
It has recently been suggested that an isotropic singularity may be a generic feature of brane cosmologies, even in the inhomogeneous case. Using the covariant and gauge-invariant approach we present...
1+1 Dimensional Compactifications of String Theory (2003)
Goheer, Naureen, Kleban, Matthew, Susskind, Leonard
We argue that stable, maximally symmetric compactifications of string theory to 1+1 dimensions are in conflict with holography. In particular, the finite horizon entropies of the Rindler wedge in 1+1...
The Trouble with de Sitter Space (2002)
Goheer, Naureen, Kleban, Matthew, Susskind, Leonard
In this paper we assume the de Sitter Space version of Black Hole Complementarity which states that a single causal patch of de Sitter space is described as an isolated finite temperature cavity...
Exponential Potentials on the Brane (2002)
Goheer, Naureen, Dunsby, Peter K. S.
In this paper we study the cosmological dynamics of Randall-Sundrum braneworld type scenarios in which the five-dimensional Weyl tensor has a non-vanishing projection onto the three-brane where...
Braneworld Dynamics of Inflationary Cosmologies with Exponential Potentials (2002)
Goheer, Naureen, Dunsby, Peter
In this work we consider Randall-Sundrum braneworld type scenarios, in which the spacetime is described by a five-dimensional manifold with matter fields confined in a domain wall or three-brane. We...