Um estudo sobre ondas gravitacionais e radiação emitida por um pulsar binário

Abstract

In this work we present a brief study about gravitational waves. We start showing Newton’s law of universal gravitation, focussing more on its historical points and implications. his law seemed to be totally right for decades, but it turned out to be imcompatible with the precession of the periheliun of Mercury. In 1915, Albert Einstein came up with a theory called General Relativity which predicts perfectly the movement of Mercury. In his theory, Einstein changes the newtonian idea of an imutable space that doesn’t have any effect over matter and events by the idea of a space-time which is always evolving in time and affects the way matter moves and the way events take place. Considering this, Einstein realised that he could change the newtoniam interpretation of gravitation, which is based on the existence of long-distance forces, by the idea of curved space-time. He idea that gravitational information can propagate is also a consequence of Einstein’s General Relativity. One of the Special Relativity postulates (also present in General Relativity), says that nothing can move faster than light. his implies that information can not be transmitted instantly, as Newton’s theory states, but it has to take some time from two different points. We call gravitation alwaves this information propagation, which is analogous to the electromagnetic waves. For distant sources (such as binary systems that we study in this paper) this gravitational radiation oscillates and its propagation is via disturbances in the also oscillating space-time, which we call gravitational waves. he existence of these waves is certainly one of the most remarkable predictions of this new theory of gravitation.We will see that these waves arise naturally as solution soft he linearized Einstein’ sequations. Accordingtothesesolutions,anydistributionsofmatterthatsuffersometemporalvariationare potential sources of gravitational radiation. However, although we know that these waves are produced by any accelerated massive body, only the most cataclysmic gravitational events in the universe produce considerable gravitational waves, such as those waves detected by LIGO observatories in an event called GW150914 which dealt with the coalescence of a pair of black holes. After this, we seek for a mathematical relation that gives us the energy emitted rate by binary systems in circular orbit via gravitational radiation. Finally, we apply the theory developed in observational data of PSR 1913+16, also known as Hulse andTaylor binary, there by obtaining a notion of the values related to this type of eventand seeing how preciseis the theory presented.