454 citations · 5.8k across the 96 of their papers we have counts for
10 papers · 1 filter
An Almost-FLRW Universe as the Averaged Geometry in Macroscopic Gravity
Anish Agashe, Mustapha Ishak
It is well-known that spacetime averaging is an operation that does not commute with building the Einstein tensor. In the framework of Macroscopic gravity (MG), a covariant averagi…
Inverse approach to Einstein's equations for fluids with vanishing anisotropic stress tensor
James Richardson, Mustapha Ishak
We expand previous work on an inverse approach to Einstein Field Equations where we include fluids with energy flux and consider the vanishing of the anisotropic stress tensor. We…
On perfect fluid models in non-comoving observational spherical coordinates
Mustapha Ishak
We use null spherical (observational) coordinates to describe a class of inhomogeneous cosmological models. The proposed cosmological construction is based on the observer past nul…
An inverse approach to Einstein's equations for non-conducting fluids
Mustapha Ishak, Kayll Lake
We show that a flow (timelike congruence) in any type warped product spacetime is uniquely and algorithmically determined by the condition of zero flux. (Though restricted,…
An Online Interactive Geometric Database: Including Exact Solutions of Einstein's Field Equations
Mustapha Ishak, Kayll Lake
We describe a new interactive database (GRDB) of geometric objects in the general area of differential geometry. Database objects include, but are not restricted to, exact solution…
Adiabatic models of the cosmological radiative era
Roberto A. Sussman, Mustapha Ishak
We consider a generalization of the Lemaitre-Tolman-Bondi (LTB) solutions by keeping the LTB metric but replacing its dust matter source by an imperfect fluid with anisotropic pres…
Stability of Transparent Spherically Symmetric Thin Shells and Wormholes
Mustapha Ishak, Kayll Lake
The stability of transparent spherically symmetric thin shells (and wormholes) to linearized spherically symmetric perturbations about static equilibrium is examined. This work gen…
The Tolman VII solution, trapped null orbits and w - modes
Nicholas Neary, Mustapha Ishak, Kayll Lake
The Tolman VII solution is an exact static spherically symmetric perfect fluid solution of Einstein's equations that exhibits a surprisingly good approximation to a neutron star. W…
Exact Solutions with w - modes
Mustapha Ishak, Luke Chamandy, Nicholas Neary +1
An explicit necessary condition for the occurrence of resonance scattering of axial gravitational waves, along with the internal trapping of null geodesics, is proposed for static…
GRLite and GRTensorJ: Graphical user interfaces to the computer algebra system GRTensorII
Mustapha Ishak, Peter Musgrave, John Mourra +2
GRLite and GRTensorJ are first and second generation graphical user interfaces to the computer algebra system GRTensorII. Current development centers on GRTensorJ, which provides f…