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Quasi-noraml and Multipole Moment for Cosmological Black Holes

Mousavian, Iman | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47504 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Mansouri, Reza; Taghizadeh Firouzjaee, Javad
  7. Abstract:
  8. Isolated black holes in equilibrium are intrinsically simple objects: They are much simpler than ordinary matter around us because they can be described by only a few parameters such as their mass, angular momentum, and charge. This simplicity, however, is apparent only because one never has an isolated black hole. Black holes in centers of galaxies or intermediate-mass black holes always have complex distributions of matter around them, such as galactic nuclei, accretion disks, strong magnetic fields, other stars, planets, etc., and are therefore actively interacting with their surroundings. However, even having been removed from all macroscopic objects and fields in space, a black hole will interact with the vacuum around it, creating pairs of particles and evaporating due to Hawking radiation. Thus, a real black hole can never be fully described by its basic parameters and is always in the perturbed state. Whenever you want to know something about stability, gravitational waves, Hawking evaporation of black holes, or about the interaction of black holes with their astrophysical environment, you have to start from an analysis of their perturbations. Moreover, the first moments after the formation of a black hole due to gravitational collapse of matter, the black hole is in a perturbed state. Once a black hole is perturbed it responds to perturbations by emitting gravitational waves whose evolution in time can be conditionally divided into three stages. But we are interest alone quasi-normal modes. because they are strong enough to detect by new antennas such as LIGO, VIRG and GEO600. From the other hand, in the theory of relativity one is used to representing the gravitation field in the neighborhood of a single black holeby the centrally symmetric static solution of the field equations, which was first stated by schwarzschild. This field goes over asymptotically with increasing distance from the generating mass into the Euclidean (or rather, Minkowskian) spase. That is to say, it is embedded in a flat space. On the other hand, we know that real space is expanding, and that, for the existence of a non vanishing average density of matter, the field equation will imply such an expanding. The black hole associated with this solution called cosmological black hole. Therefore, in this thesis first we will introduce quasinormal modes for Schwarzschild and Schwarzschildde Sitter metrics. Next it will be demonstrate that these metrics are not good one’s, therefore we will present a Appropriate cosmological black hole in Friedmann–Lemaître–Robertson–Walker background. finally a numerical method for deriving quasinormal frequency of introduced cosmological black hole will be suggested
  9. Keywords:
  10. Cosmological Black Hole ; Quasi-Normal Mode ; Multipole Moment

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