9 research outputs found
Horizons in Robinson-Trautman space-times
The past quasi-local horizons in vacuum Robinson-Trautman spacetimes are
described. The case of a null (non-expanding) horizon is discussed. It is shown
that the only Robinson-Trautman space-time admitting such a horizon with
sections diffeomorphic to S_2 is the Schwarzschild space-time. Weakening this
condition leads to the horizons of the C-metric. Properties of the hypersurface
r=2m for finite retarded time u are examined.Comment: 11
On Mason's rigidity theorem
Following an argument proposed by Mason, we prove that there are no
algebraically special asymptotically simple vacuum space-times with a smooth,
shear-free, geodesic congruence of principal null directions extending
transversally to a cross-section of Scri. Our analysis leaves the door open for
escaping this conclusion if the congruence is not smooth, or not transverse to
Scri. One of the elements of the proof is a new rigidity theorem for the
Trautman-Bondi mass.Comment: minor typos correcte
Three little pieces for computer and relativity
Numerical relativity has made big strides over the last decade. A number of
problems that have plagued the field for years have now been mostly solved.
This progress has transformed numerical relativity into a powerful tool to
explore fundamental problems in physics and astrophysics, and I present here
three representative examples. These "three little pieces" reflect a personal
choice and describe work that I am particularly familiar with. However, many
more examples could be made.Comment: 42 pages, 11 figures. Plenary talk at "Relativity and Gravitation:
100 Years after Einstein in Prague", June 25 - 29, 2012, Prague, Czech
Republic. To appear in the Proceedings (Edition Open Access). Collects
results appeared in journal articles [72,73, 122-124