Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 963 for “"Gravitational"”.
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Gravitational lensing
Gravitational lensing derives its simplicity from some basic assumptions that are satisfied by most physical situations.The thin lens approximation and weak field approximations were used to build the whole theory and explain the phenomenology up to today. We review the gravitational lensing …
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Caustics in gravitational theories
The gravitational collapse of a spherically symmetric, pressure-free dust is an interesting problem in General Relativity for it can lead, under certain initial conditions, to the situation where infinitesimally neighbouring shells approach and cross each other. The curve generated by these points …
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Cosmology through gravitational lenses
In dieser Dissertation nutze ich den Gravitationslinseneffekt, um eine Reihe von kosmologischen Fragen zu untersuchen. Der Laufzeitunterschied des Gravitationslinsensystems HE1104-1805 wurde mit unterschiedlichen Methoden bestimmt. Zwischen den beiden Komponenten erhalte ich einen Unterschied von …
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Electromagnetism in Gravitational Collapse
A numerical approach to including electromagnetism with general relativity is developed using GRAXI as a starting point. We develop a mathematical model describing electromagnetism coupled to a scalar field in an evolving axisymmetric spacetime. As there are numerous formulations of …
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Gravitational collapse, compact objects and gravitational waves in General Relativity and modified gravity
… upgraded to advanced status GW150914, the first gravitational wave signal from the inspiral and merger of two black holes was detected. The following consistent detections (9 further black hole binaries and one neutron star system) and the introduction of the European interferometer Virgo, as …
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Topics in Gravitational-Wave Astrophysics
… of different waveform models in</p> <p>gravitational wave searches for comparable mass binary black holes. We determine</p> <p>the domain of applicability of the computationally inexpensive closed form models,</p> <p>and the same for the semi-analytic models that have been calibrated to …
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Cosmological applications of gravitational lensing
In dieser Arbeit benutze ich den Gravitationslinseneffekt als ein Werkzeug, um zwei recht unterschiedliche kosmologische Fragestellungen zu bearbeiten: die Natur der dunklen Materie in Galaxienhalos und die Rotation des Universums. Zuerst untersuche ich den Mikrolinseneffekt in den …
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Gravitational waves: understanding black holes
This thesis concerns the use of observations of gravitational waves as tools for astronomy and fundamental physics. Gravitational waves are small ripples in spacetime produced by rapidly accelerating masses; their existence has been predicted for almost 100 years, but the first direct evidence of …
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Gravitational Waves in String Cosmology
… the production of cosmological backgrounds of gravitational waves in string theory models of the early universe. After a discussion of stochastic gravitational wave backgrounds, we describe the Cosmic Gravitational Wave Background (CGWB), its sensitivity to ultra-violet physics, and provide …
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Discrete gravitational approaches to cosmology
… an exact solution is not available, discrete gravitational approaches can approximate the system instead. This thesis investigates several cosmological systems using two distinct discrete approaches. Closed, flat, and open ‘lattice universes’ are first considered where matter is distributed as …
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Gravitational Lensing and Telescope Aberrations
… each of which addresses challenges to weak gravitational lensing flexion measurements. Part one is a derivation and analysis of the aberration shapes and patterns imparted onto images by misaligned telescopes. As telescope aberrations will generally interfere with lensing measurements, it is …
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Gravitational radiation detectability of supernova 1987A's remnant fully matched filter for double resonant gravitational detector
… is believed to spin down due to the emission of gravitational waves. We give a precise calculation of the strain value of the gravitational waves reaching earth and discuss the possibility of detection of this radiation by existing and soon on line gravitational waves detectors. Our conclusion is …
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Defining gravitational singularities in general relativity
… classify curvature singularities as either gravitational or non-gravitational. In general relativity, a curvature singularity is ``located'' where the scalar invariants of the spacetime are undefined. The gradient field of a non-zero scalar invariant can then be calculated, and the end …
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Gravitational wave extraction in numerical relativity
… thus most interesting source for the study of gravitational waves, a prediction of general relativity, is the merger of two black holes. To understand the generation and evolution of gravitational waves in such a case, extensive efforts have been made. One is the construction of highly …
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Data analysis of continuous gravitational waves
… detectors we do not expect to detect any true Gravitational Wave signals in our data, we can still set upper limits on the strength of the gravitational waves signals. These upper limits, in fact, tell us how weak a signal strength we would detect. We have also used our software to set upper …
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Cylindrically symmetric models of gravitational collapse
… of generalising the Oppenheimer-Snyder model of gravitational collapse to the cylindrically symmetric case The second problem is an analysis of cylindncally symmetric spacetimes with self-similarity modelling gravitational collapse The field equations and regularity conditions are examined …
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Gravitational Instabilities in a Rotating Fluid
Made available in DSpace on 2014-12-13T18:55:31Z (GMT). No. of bitstreams: 1 7606984.pdf: 6669099 bytes, checksum: db28e57760a633e72e70911875a7fae2 (MD5) Previous issue date: 1975
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Interstellar Gravitational Perturbations of Cometary Orbits
Made available in DSpace on 2014-12-12T00:17:47Z (GMT). No. of bitstreams: 1 7212154.pdf: 2691518 bytes, checksum: 30ec6fe43239395eef63314798ecafec (MD5) Previous issue date: 1971
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Radio-polarimetric observations of gravitational lenses
… observational radio-polarimetric properties of gravitational lens systems. Such studies can constrain lensed source properties, propagation effects in the intervening lensing galaxies, and the general-relativistic invariance of polarization under lensing. We performed high dynamic-range VLBI …
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