Speaker: Nigel Bishop (Rhodes University)
Title: Propagation of gravitational waves through matter using the Bondi-Sachs formalism
Gravitational waves propagate through cosmological matter (for which the properties of the dark matter are largely unknown), and perhaps also through matter in the local environment of the source. This issue has received previous attention, and here we use the Bondi-Sachs formalism, which has given additional insights in other cases. We construct exact solutions to the linearized Einstein equations, when the background density is spherically symmetric with specific functional forms for the radial dependence. However, that is sufficient to be able to obtain expressions for the effect of a thin shell, and then a general density distribution can be modelled by integration over a sequence of thin shells. We find that, although energy is not extracted, the dust shell does cause a gravitational wave to be modified.
Room: Sala de Reuniões e Seminários (2nd Floor of physics building)