A. Sherif

collaborators

6 papers

gr-qc2026

Geodesic completeness of anisotropic cosmologies and the null energy condition

Sebastian Garcia-Saenz, Junjie Hua, Abbas M. Sherif

We demonstrate that a Bianchi-I spacetime in general relativity must be geodesically past-incomplete under the assumption of the null energy condition and provided there exists a t…

gr-qc2026

Conformal symmetries and MOTS stability

Abbas M. Sherif

Let ${I^£_{t}}$ be a spacelike foliation of a spacetime $M$ , and suppose each $I^£_{t}$ is foliated by 2-surfaces $S$ with spacelike unit normal in $I^£_{t}$ . We show…

gr-qc2026

A complete correspondence between the Newman-Penrose and 1+1+2 formalisms

Abbas M Sherif, Peter K S Dunsby

We establish a correspondence between the Newman-Penrose and 1+1+2 semitetrad covariant formalisms by expressing all Newman-Penrose spin coefficients, Ricci scalars, and Weyl scala…

gr-qc2026

Interior marginally outer trapped surfaces in Hayward black holes

Abbas M. Sherif, Yen-Kheng Lim

We locate interior marginally outer trapped and marginally outer trapped open surfaces (MOTS/MOTOS) in the regular Haward metric with parameter $b$ for which a critical (extremal)…

math.DG2025

Instability of marginally outer trapped surfaces from initial data set symmetry

Abbas M. Sherif

Let $(I^~ £, h_{ab}, K_{ab})$ be an initial data set and let $x^{a}$ be a symmetry vector of $I^~ £$ . Consider a MOTS $S$ in $I^~ £$ and let the symmetry vector be d…

gr-qc2025

On conformal Komar currents in LRS spacetimes

Abbas M. Sherif

For locally rotationally symmetric (LRS) spacetimes, we construct two equivalent forms of the Komar current derived from a conformal Killing vector. One is a kinematic construction…