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 281 for “"Black Holes"”.
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Demographics of supermassive black holes
Supermassive black holes are a fundamental component of the universe in general and of galaxies in particular. Almost every massive galaxy harbours a supermassive black hole (SMBH) in its center. Furthermore, there is a close connection between the growth of the SMBH and the evolution of its host …
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Black holes with a twist
… theory on orbifolds of AdS3. Non-extremal BTZ black holes have been shown to oer a good opportunity to study closed string tachyon condensation, as there are tachyons in the winding sector even in superstring theory. We study extremal BTZ black holes, both M = 0 and M = J from a world sheet …
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Gravitational waves: understanding black holes
… the gravitational field around an astrophysical black hole conforms to the predictions of general relativity and the cosmic censorship hypothesis. It is expected that the gravitational field should be well described by the famous Kerr solution. Two approaches for testing this hypothesis are …
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BLACK HOLES AND SOLUTION GENERATING TECHNIQUES
Multi-black hole solutions play a relevant role both from the theoretical and the phenomenological point of view. In this Thesis, we construct some regular multi-black hole spacetimes in pure Einstein’s General Relativity with the aid of solution generating techniques. We begin with a perspective …
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Quantum Fields on BTZ Black Holes
… some aspects of Quantum Fields on BTZ black holes in 1+1 and 1+2 dimensions. More specifically, we study how a ground state in AdS spacetime becomes a thermal state when restricted to the exterior region of the BTZ black hole. This ground state is for the quantum linear real scalar …
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Advances in Simulating Binary Black Holes
… phenomena in the Universe, the mergers of two black holes. The success of gravitational-wave astronomy is inseparable from the advances in numerical relativity. Nowadays, numerical relativists are able to simulate the spacetimes of binary-black-hole mergers routinely and extract accurate …
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Traversable Wormholes in Kerr Black Holes
Wormholes have long been a source of interest in general relativity, having been first coined by John Wheeler in 1957. More recently, wormholes have proven instrumental to our understanding of quantum gravity, with particular interest being given to Euclidean wormholes and their relevance to the …
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Radiation transport around Kerr black holes
… for analyzing accretion processes around Kerr black holes. We begin in Chapter 1 with a brief historical summary of the major advances in black hole astrophysics over the past few decades. In Chapter 2 we present a detailed description of the ray-tracing code, which can be used to calculate the …
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Optimal Reinforcement Learning with Black Holes
We introduce the Black Hole Reinforcement Learning problem, a previously unexplored variant of reinforcement learning in which we lose all turn information and all reward from trajectories that visit a particular subset of states. We assume awareness of the trajectory loss events, making this a …
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Modular properties of higher spin black holes
… of the thermodynamic properties of higher spin black holes in AdS3. Through the conjectured Minimal Model/Higher Spin duality, the partition functions of such black holes should be equal to partition functions in the presence of chemical potentials in an appropriate dual 2d CFT. In the …
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Dense stellar systems and massive black holes
… of the cardinal predictions of this theory are black holes. Massive, dark objects are found in the majority of galaxies. Our own galactic center very contains such an object with a mass of about four million solar masses. Are these objects supermassive black holes (SMBHs), or do we need …
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Time-dependent Accretion Flows onto Black Holes
… systems like active galactic nuclei (AGN) and black hole X-ray binaries (BHXB). The standard thin disk model fails to reproduce the spectra of these systems. They exhibit a blackbody-like component, generally attributed to the cold standard disk, and a hard power law-like component extending to …
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Quasinormal Modes of Nearly Extremal Black Holes
… striking a bell; like many physical systems, black holes emit radiation as a response to perturbations. After a dynamical event, for example a black hole merger, the system is expected to relax to a stationary black hole solution. After sufficient time, the system can be treated as a …
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Black Holes, Galaxy Clusters and Gravitational Waves
… s, in concert with the established Luminosity -- Black Hole mass relation, we calculate the mass distribution of supermassive massive black holes (SMBHs) and Active Galactic Nuclei (AGNs) in three different environments. SMBHs and radio-AGNs are concentrated in dense environments. The Black Hole …
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Classical and thermodynamic stability of black holes
We consider the stability of black holes within both classical general relativity and the semiclassical thermodynamic description. In particular, we study linearised perturbations and their contributions to the gravitational partition function. Exploring the connection between classical and …
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Spectra and variability of accreting black holes
… concerning the structure of matter close to black holes when they are actively accreting. The two components (apart from the black hole itself) most relevant to this work are the accretion disc and X-ray emitting corona. We use various methods to help determine their location, properties and …
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Production and evaporation of higher dimensional black holes
… the theory and phenomenology of trans-Planckian black holes, in TeV gravity extra-dimensional theories. The introduction starts with the motivation for this beyond the Standard Model scenario (chapter 1), a summary of the theoretical tools to formulate the theory, and a summary of the best bounds …
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Hunting Supermassive Black Holes in the Early Universe
Supermassive black holes (SMBHs) hold the essential ingredient into understanding the galaxy formation and evolution across cosmic time. The physical properties of SMBH are found to tightly correlated with host galaxies in local universe. Whether such relationship apply in the early universe …
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Building Black Holes: Analogue experiments and analogical reasoning
Analogue experiments investigate empirically accessible ‘source’ systems that are meant to mirror the behaviour of less accessible ‘target’ systems. This disseration aims to answer two questions about analogue experiments. First, what are they useful for? Second, how do analogical reasoning and the …
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ANALYZING AND IMPROVING INITIAL DATA FOR BINARY BLACK HOLES
Binary black holes are one of the most likely sources of gravitational radiation to be detected by projects such as LIGO and LISA. This radiation causes the binary to lose energy and angular momentum with the black holes adiabatically spiraling together. The strongest radiation is emitted at …
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