A numerical-relativity calculation yields in general a solution of the Einstein equations
including also a radiative part, which is in practice computed in a region of finite extent …

A priori, there is nothing very special about shear-free or asymptotically shear-free null
geodesic congruences. Surprisingly, however, they turn out to possess a large number of …

Given the important role that the galaxy bispectrum has recently acquired in cosmology and
the scale and precision of forthcoming galaxy clustering observations, it is timely to derive …

Spin-weighted spherical functions provide a useful tool for analyzing tensor-valued functions
on the sphere. A tensor field can be decomposed into complex-valued functions by taking …

The spin-coefficient formalism (SC formalism)(also known in the literature as Newman-
Penrose formalism (NP formalism)) is a commonly used technique based on the use of null …

The asymptotic approach derived by Kozameh-Quiroga provides a modern framework to
obtain the evolution of global variables of isolated sources of gravitational radiation. We test …

A brief review about the Newman-Penrose formalism and the asymptotic structure of the
spacetime is given. The goal of this review is to describe the latest developments in these …

In this work we analyze the similarities and differences between the equations of motion for
the center of mass and intrinsic angular momentum for isolated sources of gravitational …

We define the center of mass and spin of an isolated system in general relativity. The
resulting relationships between these variables and the total linear and angular momentum …

The center of mass (cm) and spin for isolated sources of gravitational radiation that move at
relativistic speeds are defined. As a first step we also present these definitions in flat space …