Emisión y propagación de ondas gravitacionales en fusiones de sistemas binarios

Abstract

We analyze the phenomena of emission of Gravitational Waves focusing on a binary system of compact objects. This cutting edge topic has experienced a lot of advances on the recent years. The first observation of Gravitational Waves on 2015 opened a window to obtain new information from our universe. Multi-messenger astronomy let us receive signals from electromagnetic radiation, neutrinos, cosmic rays and now Gravitational Waves are added to the list. But, building accurate detectors is not enough. To separate the signal of Gravitational Waves from the noise it is necessary to rely on a good prediction of the wavefront. This is not an easy task due to the non-linearity of General Relativity. We will focus on the first phase of the collision of compact objects where the objects follow an inspiral orbit. As a first approximation, we use the multipole expansion on the typical velocities of the source, working on linearized theory. We compute the wavefront and the power carried by the Gravitational Waves for a binary system taking only the leading term on the multipole expansion (mass quadrupole). The next step would be to apply the Post-Newtonian formalism, which is valid for self-gravitating systems in the region near the source. This is an expansion on low velocities and weak gravitational field that takes into account the non-linearity of General Relativity. We analyze how this expansion works and compute the general expression of the metric tensor components up to 1PN order in terms of static potentials. Finally, we provide some information about the other phases of black holes mergers and about the signal emitted.