Tesis doctoral de Priscilla Cañizares Martínez
Extreme-mass-ratio inspirals are one of the main sources of gravitational waves (gws) for spatial detectors like the future laser interferometer space antenna (lisa). These are binary systems which are made up of a stellar compact object (sco) and a massive black hole (mbh) located in a galactic centre. emris emit long and complex gws signals in the strong field regime of the mbhs, which encode the mbh structure. For this reason, emri gw signals are a valuable tool to study the mbhs located in the galactic centres and the science related with them. In this thesis, we study two different aspects of emris. The first part of the thesis is devoted to the modelling of emris. To produce the gw waveforms needed for emri detections, we have to know how the gravitational field of the sco affects its own trajectory and deviates it from geodesic motion. In this regard, due to the extreme mass-ratio of the system, we can consider the sco as a structureless particle orbiting in a geodesic of the exact mbh geometry. In this picture, the inspiral of the sco around the mbh is described through the action of a local self-force, which alters the geodesic motion of the particle. However, the implementation of this mechanism presents several difficulties, mainly due to the point-like description of the sco, which introduces dirac delta distributions. This in practice means that one has to deal with very different spatial scales, one associated with the modelling of the sco and another associated with the mbh. Moreover, the extreme mass ratio of these systems implies that we have to deal with two different time scales in the dynamics of the system, one associated with the orbital evolution of the sco and another associated with the evolution of its orbit due to gwemission. We present a new method that provides very efficient and accurate computations of the self-force in the time-domain, which makes our technique amenable for the intensive computations required in the astrophysically relevant scenarios. The key point of our scheme is that it does not need to resolve the sco. Instead, we avoid its presence in the computational domain by substituting the dirac delta distributions by boundary conditions. Consequently, we have just to provide the numerical resolution to describe the field near the sco, but not the sco itself. the second part of the thesis we investigate whether we can use emri observations to test a particular theory of gravity, namely dynamical chern-simons modified gravity (dcsmg) theory. The idea is that the sco orbits are deep inside the mbh gravitational potential, that is, emri systems emit gws from the strong field region of the mbh. In this way, the shape and timing of the gws emitted by the system have encoded the structure of the mbh spacetime and the way in which the characteristic frequencies of the system evolve. This information allows us to perform tests of gr and even of other theories of gravity. We perform this study using fisher matrix analysis.
Datos académicos de la tesis doctoral «Extreme-mass-ratio inspirals: modelling and test of an alternative theory of gravity«
- Título de la tesis: Extreme-mass-ratio inspirals: modelling and test of an alternative theory of gravity
- Autor: Priscilla Cañizares Martínez
- Universidad: Autónoma de barcelona
- Fecha de lectura de la tesis: 21/10/2011
Dirección y tribunal
- Director de la tesis
- Carlos Fernández Sopuerta
- Tribunal
- Presidente del tribunal: José alberto Lobo gutierrez
- leor Barack (vocal)
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