Gravitational radiation, and applications of the characteristic formalism
The upgrade program to improve the sensitivity of the gravitational radiation detectors
LIGO and VIRGO has already started, and is scheduled for completion in 2014. The first
confirmed signals could therefore be expected to be detected in 2014 or thereafter.
The first part of this talk reviews the whole field of gravitational radiation detection,
including detector sensitivities, astrophysical sources and their expected rates and
magnitudes, data analysis of detector data, and the calculation of templates of waveforms
needed for the data analysis.
The second part of the talk reviews the characteristic approach to the calculation of
gravitational waveforms, in which the coordinates are constructed based on outgoing
light cones. The method has particular advantages in the accurate computation of
gravitational radiation. Another application is to cosmology, since nearly all
cosmological data is a result of observations on our past light cone. It is in
principle possible to use observed data and compute the past behaviour of the universe,
and such codes have been implemented. The characteristic approach can also be used
to construct linearized Einstein equations by means of which gravitational radiation
can be calculated analytically.