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Bondi mass-loss without gauge simplifications

Project: 
It is well known that the Bondi-mass on null infinity for asymptotically flat space-times is non-increasing toward future timelike infinity. This formula is explicitly derived (for example in the Spinor and Space-time books by Penrose and Rindler) by making assumptions about the conformal factor and gauge on null infinity to simplify the calculations. There are only a few numerical frameworks able to compute asymptotically flat space-times where null infinity is included in the computation domain, of which the most noteworthy is the initial boundary value formulation of the conformal field equations. This formulation fixes a conformal factor for the whole space-time based on the initial data set. In general this conformal factor cannot be chosen to satisfy the simplifying assumptions of Penrose and Rindler and thus their expressions for the Bondi-mass and the accompanying mass-loss formula are not valid. The aim of this project is to rigorously derive the relevant equations necessary to express the Bondi-components on null infinity, and thus the mass-loss formula, without making the simplifying assumptions of Penrose and Rindler. These expressions will then be directly applicable to the conformal field equation framework of C. Stevens et al.
Node This Project Is Offered On: 
(UCT)(UKZN)(NWU)

Supervisor

Chris
Stevens

Co-Supervisor

Requirements for students to address: 
Basis knowledge of general relativity would be an advantage.
Research Area: 
General Astrophysical Sciences


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