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Ahmadi, Morteza, and University of Lethbridge Faculty of Arts and Science. "Aspects of black hole physics." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2006, 2006. http://hdl.handle.net/10133/386.
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In this thesis, aspects of the physics of black holes are reviewed and new results in
black hole thermodynamics are presented. First, general black hole solutions of Einstein’s equations of general relativity are mentioned and a proof of conservation law of energy and momentum in general relativity is presented. Aspects of the laws of black hole mechanics and Hawking radiation are then studied. Two proposals which attempt to explain the origin of black hole entropy (the brick wall model and entanglement entropy) are then discussed. Finally, some recent work related to the possible production and detection of black holes in colliders is presented.viii, 141 leaves ; 29 cm.
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Chung, Hyeyoun. "Exploring Black Hole Dynamics." Thesis, Harvard University, 2014. http://nrs.harvard.edu/urn-3:HUL.InstRepos:14226081.
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This thesis explores the evolution of different types of black holes, and the ways in which black hole dynamics can be used to answer questions about other physical systems.
We first investigate the differences in observable gravitational effects between a four-dimensional Randall-Sundrum (RS) braneworld universe compared to a universe without the extra dimension, by considering a black hole solution to the braneworld model that is localized on the brane. When the brane has a negative cosmological constant, then for a certain range of parameters for the black hole, the intersection of the black hole with the brane approximates a Banados-Teitelboim-Zanelli (BTZ) black hole on the brane with corrections that fall off exponentially outside the horizon. We compute the quasinormal modes of the braneworld black hole, and compare them to the known quasinormal modes of the three-dimensional BTZ black hole. We find that there are two distinct regions for the braneworld black hole solutions that are reflected in the dependence of the quasinormal modes on the black hole mass. The imaginary parts of the quasinormal modes display phenomenological similarities to the quasinormal modes of the three-dimensional BTZ black hole, indicating that nonlinear gravitational effects may not be enough to distinguish between a lower-dimensional theory and a theory derived from a higher-dimensional braneworld.
Secondly, we consider the evolution of non-extremal black holes in N=4, d=2 supergravity, and investigate how such black holes might evolve over time if perturbed away from extremality. We study this problem in the probe limit by finding tunneling amplitudes for a Dirac field in a single-centered background, which gives the decay rates for the emission of charged probe black holes from the central black hole. We find that there is no minimum to the potential for the probe particles at a finite distance from the central black hole, so any probes that are emitted escape to infinity. If the central black hole is BPS in the extremal limit, then the potential is flat and so there is no barrier to the emission of probes. If the central black hole is non-BPS in the extremal limit, then there is a barrier to emission and we compute the decay rate, which depends both on the charge of the central black hole and the charges of the emitted black holes.
Finally, we consider the possibility that an extremal black hole, the end-point of the evolution of a non-extremal black hole through evaporation, may itself split into a multi-centered black hole solution through quantum tunneling, via a gravitational instanton analogous to the instanton for the symmetric double well in elementary quantum mechanics. We find a gravitational instanton that connects two vacuum states: one state corresponding to a single-centered extremal Reissner-Nordstrom (ERN) black hole configuration, and another state corresponding to a multi-centered ERN configuration. We evaluate the Euclidean action for this instanton and find that the amplitude for the tunneling process is equal to half the difference in entropy between the initial and final configurations.
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Luna, Raimon. "New Strategies for Black Hole Physics." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/669583.
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In this thesis we apply new approaches and develop new techniques to address various issues related to fundamental aspects of modern gravitational theory and black holes.
We study the behavior of black branes in the large D approximation, that is, we consider a space with a very large number of dimensions. This approach allows us to obtain a set of very simple equations that capture many of the physical phenomena of gravity. This technique uses the fact that the gravitational field around a massive object decays faster the higher the dimension, so when you take the very large D limit it becomes concentrated in a very thin region of size 1/D around the horizon of the black hole. In this way, the horizon can be viewed as a membrane suspended in an essentially flat background geometry. The region where the black hole lives is, in some sense, excluded from the background space.
We use the large D effective equations to investigate the phases and stability of black strings at different values of the dimension D and the compactification length L. In some cases, the Gregory-Laflamme instability of the uniform black strings can lead to stable non-uniform black strings. The transition type changes at a certain critical value of D ~ 13.5. We use 1/D corrections to estimate the value of the critical dimension, which turns out to be very accurate.
Possible violations of Weak Cosmic Censorship in black hole collisions at D > 4 are also explored. The large D technique, through the effective equations, provides a powerful tool for analyzing such scenarios that would otherwise be very difficult to tackle using numerical simulations at finite D. It has recently been shown that rotating black holes can be described as Gaussian lumps on a black brane.
The Strong Cosmic Censorship conjecture for highly charged Reissner-Nordström black holes has recently been called into question in asymptotically de Sitter spacetimes. To go beyond previous studies, this thesis includes the results of nearly extremal Reissner-Nordström nonlinear simulations. In order to perform the nonlinear (spherically symmetric) integrations, a new spectral code has been developed in double-null coordinates.
Any continuous system that can be described as a quantum field theory will react to a change in the geometry where it is located. It will do so by changing its distribution of energy density, pressure and stresses. That is, the system is polarized, and its stress-energy tensor acquires a non-trivial quantum expectation value. In this context, the holographic duality, also known as AdS/CFT correspondence, is extremely useful for extracting valuable qualitative information from the system. Perturbations of the geometry of the AdS boundary will produce tidal deformations in the geometry of the bulk. To calculate this deformations, we solve the equations for a linearized perturbation of the geometry that satisfies suitable boundary conditions.
Finally, we study a subset of Horndeski's theories whose equations of motion are locally well posed. However, it is necessary to determine whether global solutions exist and whether they are sufficiently well behaved. A worrisome possibility (which has been confirmed by numerical simulations) is a change in the character of the equation of motion, from hyperbolic to parabolic and finally to elliptical. This causes a change in the causal structure of the geometry.En aquesta tesi aplicarem nous enfocaments i desenvoluparem noves tècniques per tractar diversos temes relacionats amb aspectes fonamentals de la teoria gravitacional moderna i els forats negres. Estudiem el comportament de les branes negres en l’aproximació large D, és a dir, considerem un espaitemps amb un nombre molt gran de dimensions. Aquest enfocament ens permet obtenir un conjunt d’equacions molt simples que recullen molts dels fenòmens físics de la gravetat. En alguns casos, la inestabilitat de Gregory-Laflamme de les cordes negres uniformes pot conduir a cordes negres no uniformes estables. S’exploren també possibles esdeveniments de violació de la Censura Còsmica Feble en col·lisions de forats negres a D > 4. La tècnica de large D, mitjançant les equacions efectives, proporciona una eina potent per analitzar aquest tipus d’escenaris que d’altra manera serien molt complicats d’abordar mitjançant simulacions numèriques a D finita. Recentment s’ha posat en dubte la conjectura de Censura Còsmica Forta per a forats negres de Reissner-Nordström altament carregats en espaitemps asimptòticament de Sitter. Per anar més enllà dels estudis anteriors, en aquesta tesi s’inclouen els resultats de simulacions completament no lineals de Reissner-Nordström altament carregats. Qualsevol sistema continu que es pugui descriure com una teoria quàntica de camps reaccionarà davant un canvi en la geometria on està situat. En aquest context, la correspondència AdS/CFT és extremadament útil per extreure informació qualitativa i valuosa del sistema. Les pertorbacions en la geometria de la frontera d’AdS produiran deformacions de marea en la geometria de l’interior. Per calcular aquesta deformació, resolem les equacions per a una pertorbació linealitzada de la geometria que satisfà una condició de contorn adequada a l’infinit. Finalment, s’estudia un subconjunt de les teories de Horndeski les equacions del moviment de les quals són localment ben plantejades. Tot i això, cal determinar si existeixen solucions globals i si aquestes solucions són prou ben comportades. Una possibilitat preocupant (que s’ha confirmat amb simulacions numèriques), és un canvi del caràcter de l’equació de moviment, d’hiperbòlica a parabòlica i finalment a el·líptica.
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Pidokrajt, Narit. "Information geometries in black hole physics." Doctoral thesis, Stockholms universitet, Fysikum, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-29365.
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In this thesis we aim to develop new perspectives on the statistical mechanics of black holes using an information geometric approach (Ruppeiner and Weinhold geometry). The Ruppeiner metric is defined as a Hessian matrix on a Gibbs surface, and provides a geometric description of thermodynamic systems in equilibrium. This Ruppeiner geometry exhibits physically suggestive features; a flat Ruppeiner metric for systems with no interactions i.e. the ideal gas, and curvature singularities signaling critical behavior(s) of the system. We construct a flatness theorem based on the scaling property of the black holes, which proves to be useful in many cases. Another thermodynamic geometry known as the Weinhold geometry is defined as the Hessian of internal energy and is conformally related to the Ruppeiner metric with the system’s temperature as a conformal factor. We investigate a number of black hole families in various gravity theories. Our findings are briefly summarized as follows: the Reissner-Nordström type, the Einstein-Maxwell-dilaton andBTZ black holes have flat Ruppeiner metrics that can be represented by a unique state space diagram. We conjecture that the state space diagram encodes extremality properties of the black hole solution. The Kerr type black holes have curved Ruppeiner metrics whose curvature singularities are meaningful in five dimensions and higher, signifying the onset of thermodynamic instabilities of the black hole in higher dimensions. All the three-parameter black hole families in our study have non-flat Ruppeiner and Weinhold metrics and their associated curvature singularities occur in the extremal limits. We also study two-dimensional black hole families whose thermodynamic geometries are dependent on parameters that determine the thermodynamics of the black hole in question. The tidal charged black hole which arises in the braneworld gravity is studied. Despite its similarity to the Reissner-Nordström type, its thermodynamic geometries are distinctive.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted.
Geometry and Physics
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Chambers, Chris M. "Classical aspects of black hole physics." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294892.
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Zhu, Yucong. "The Bright Side of Black Holes: Radiation From Black Hole Accretion Disks." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17463143.
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An understanding of radiation is paramount for connecting observations of accretion disks with the theory of black holes. In this thesis, we explore via radiative transfer postprocessing calculations the observational signatures of black holes. We investigate disk spectra by analyzing general relativistic magnetohydrodynamic (GRMHD) simulations of accretion disks. For the most part there are no surprises -- the resulting GRMHD spectrum is very close to the analytic Novikov & Thorne (1973) prediction from decades past, except for a small modification in the case of spinning black holes, which exhibit a high-energy power-law tail that is sourced by hot Comptonized gas from within the plunging region of the accretion flow. These conclusions are borne out by both 1D and 3D radiative transfer calculations of the disk. Significant effort was spent in developing from scratch the 3D radiative code that we used for the analysis. The code is named HERO (Hybrid Evaluator for Radiative Objects) and it is a new general purpose grid-based 3D general relativistic radiative solver.Astronomy
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O'Sullivan, Stephen Gerard. "Making better binary models and modeling distorted black holes using black hole perturbation theory." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99297.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references.
In this thesis, I discuss the application and development of black hole perturbation theory both from an observational standpoint via gravitational waves and also tidal distortions of black hole horizons. The promise of gravitational wave astronomy depends on our ability to accurately model gravitational wave signals from astrophysical sources. This requires large numbers of accurate theoretical template waveforms spanning large regions of parameter space to be cross-correlated against the output of gravitational-wave detectors. Numerical simulations of binary black-hole evolution are now possible but remain CPU costly. They also have problems with small mass ratios where perturbative analyses are efficient. This high computational cost has motivated the development of the effective-one-body (EOB) formalism, a framework which models the three phases of binary black hole coalescence - inspiral, plunge/merger, and ring down - by combining information from a variety of modeling techniques. In this thesis, we combine EOB with black hole perturbation theory to study the transition from inspiral to plunge-merger and ringdown. This allows us to tune and improve the accuracy of EOB. In Newtonian gravity, tidal coupling between members of a binary system has an influence on that binary's dynamics. There are also well-understood connections between the geometry of the binary's distorted members and the impact of tides on the orbit's evolution. In this thesis we develop tools for investigating the tidal distortion of black holes for tides arising from a body in a bound orbit. We also develop tools to visualize the horizon's distortion for black hole spin a/M < V/3/2. In analyzing how a Kerr black hole is distorted by a small body for a circular equatorial orbit, we find that Newtonian intuition is not applicable. We also apply these techniques to generic Kerr black hole orbits, which enables us to look at time-dependent phenomena on the horizon. In particular, we find significant offsets between the applied tide and the horizon's response, as well as small amplitude coherent wiggles in the horizon's shear response to the applied tide. These appear to arise from the teleological nature of the horizon's response to tides.
by Stephen Gerard O'Sullivan.
Ph. D.
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Sung, Shih-Ta. "Black hole entropy and models." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4677/.
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No universally accepted statistical explanation of black hole entropy exists up to now, therefore, it is worth another try. Admittedly, black hole entropy does not have to have a statistical origin. If the "black hole entropy" is called "black hole index" instead, someone might be lured to give it an economic explanation. Nonetheless, the only way to justify one's claim about the statistical origin of black hole entropy is to compute it statistically. This is the motivation for the construction of black hole models. In chapter 1, I first review the four laws of classical black hole mechanics which form the basis for the introduction of black hole thermodynamics. After observing the formal analogy between the four laws of the black hole mechanics and that of the ordinary thermodynamics, I further explore the thermodynamic properties of black holes in chapter 2 by reviewing the phenomenon of Hawking radiation and introducing the idea of black hole entropy. Three statistical explanations of black hole entropy are introduced in chapter 3. I will start with’t Hooft's brick wall model. Then, á la Brown and York, I review the approach based on the gravitational degrees of freedom via path integral. In the final part of this chapter, I present my own version of a quantum statistical explanation of black hole entropy by regarding a black hole as a cavity with thermal states inside. The final chapter will be devoted to the construction of black hole models to materialise the idea that a black hole, in some sense, can be regarded as a cavity where thermalised quantum states reside with quantised spectrum. These quantum states and the corresponding spectrum will then justify the statistical explanation of black hole entropy presented in the final section of chapter 3.
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Kolishetty, Kiran. "Quantum properties of black hole." Thesis, Lancaster University, 2014. http://eprints.lancs.ac.uk/71783/.
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In this research report I would like to present some of the results obtained based on the published research, it is on the analogue model of Bose Einstein condensate of gravitons. In my investigation with different approach I could reach similar conclusion for Schwarzschild radius which is derived for Bose Einstein condensate of N-gravitons . I could calculate the pressure inside the condensed black hole. It is found that the Bogoliubov dispersion relation for the elementary excitations of the weakly-interacting N-gravitons is shown to hold for the case of the weakly-interacting Graviton gas or N weakly interacting gravitons. where both the cases of attraction and repulsion is taken into consideration between the weakly coupled N-gravitons. It is interesting to notice that weakly interactions among gravitons have differences in attractive and repulsive case, additionally I will be looking into the possible way to understand the entropy of the N-graviton in a condensed Black hole. Finally I could derive the critical point for Black hole for N gravitons in case of weakly attractive interacting N gravitons , In attractive nature of N-gravitons I found that it has critical point at which black holes do not form the condensate , above this critical value k Black hole seems to form a condensate of N-gravitons. In this approach Black hole entropy is understood from condensed matter physics perspective as excited states of condensed matter of N-gravitons. Furthermore, this includes the literature review in order to support the results obtained in my calculations.
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Sidhu, Steve. "Conformal field theory and black hole physics." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Physics and Astronomy, c2012, 2012. http://hdl.handle.net/10133/3109.
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This thesis reviews the use of 2-dimensional conformal field theory applied to gravity,
specifically calculating Bekenstein-Hawking entropy of black holes in (2+1) dimensions.
A brief review of general relativity, Conformal Field Theory, energy extraction
from black holes, and black hole thermodynamics will be given. The Cardy formula,
which calculates the entropy of a black hole from the AdS/CFT duality, will be shown
to calculate the correct Bekenstein-Hawking entropy of the static and rotating BTZ
black holes. The first law of black hole thermodynamics of the static, rotating, and
charged-rotating BTZ black holes will be verified.vii, 119 leaves : ill. ; 29 cm
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Di, Criscienzo Roberto. "Semi-classical aspect of black hole physics." Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/367865.
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Di, Criscienzo Roberto. "Semi-classical aspect of black hole physics." Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/627/1/PhD_v2.pdf.
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Adams, N. "Symmetry restoration near a black hole." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372638.
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PANI, PAOLO. "Applications of perturbation theory in black hole physics." Doctoral thesis, Università degli Studi di Cagliari, 2011. http://hdl.handle.net/11584/266254.
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Black holes have many faces. Arguably, they are the most interesting objects in theoretical physics, revealing the elusive connection between gravity and quantum mechanics. Within the gauge/string duality they provide useful insights on strongly coupled quantum field theories
and on quantum gravity. Furthermore, probing the strong curvature regime of any gravity theory, black holes carry the imprint of possible strong curvature corrections to General Relativity. Finally, beside their unique theoretical properties, several experimental evidences
suggest that astrophysical black holes exist in nature and they are believed to be very common objects in the universe. In this dissertation we discuss several applications of linear perturbation theory in black hole physics. As applications in theoretical physics, we study
perturbations of dilatonic black holes in Einstein-Maxwell theory and the holographic properties of the dual field theory via the Anti de Sitter/Condensed Matter duality. Furthermore we discuss a method to compute long-lived quasinormal modes of Schwarzschild-Anti de Sitter
black holes and we study vortex black hole solutions in three dimensional Anti de Sitter gravity. As applications in astrophysics, we discuss how the characteristic oscillations of black holes in string-inspired theories of gravity can provide observable signatures of deviations from
General Relativity. We study two well-motivated effective theories: Dynamical Chern-Simons gravity and Einstein-Dilatonic-Gauss-Bonnet gravity. We conclude by discussing the black hole paradigm. Motivated by the lacking of a definitive answer on the existence of astrophysical
black holes, we study some viable alternatives, generally called “black hole mimickers”. We focus on two representative cases: static thin-shell gravastars and superspinars. We discuss their stability, gravitational-wave signature and viability as astrophysical objects.
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Schulz, Michael B. (Michael Brian). "Theory of accelerated detectors and black hole radiation." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/105016.
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Misra, Ranjeev. "The spectral characteristics of galactic black hole systems." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290618.
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The hard X-ray spectrum from black hole candidates, such as 1E1740.7-2942 and Cygnus X-1, has been attributed to an inner hot (Tₑ ≈ 10⁹ K) two-temperature disk which Comptonizes externally produced soft photons from the outer disk. We developed a natural extension of this model, wherein the innermost region of the two-temperature disk, is much hotter (Tₑ ≈ 5 x 10⁹ K) since it is shielded from the external photons and is forced to cool via bremsstrahlung self-comptonization. The emission from this region can account for the long term γ-ray variability in Cygnus X-1. The e⁺e⁻ pairs produced above the hot plasma give rise to the annihilation line observed in 1E1740.7-2942 and the residual pairs form the extended radio jets observed in this source. These early successes called for more detailed modeling of the hot disk. The effects of e⁺e⁻ pairs produced inside the disk were investigated using a better technique for the Comptonization process than what had been reported previously in the literature. This has important quantitative (but no qualitative implications) on the model. Another crucial effect is that of the proton thermal energy being advected to smaller radii. This makes the disk sensitive to the outer boundary conditions (i.e the structure of the transition zone between the outer cold disk and the inner hot region). To determine the physics of the transition region we have developed a scheme for the radiative cooling which is valid at all optical depths. The application of this scheme revealed that the transition region is an extended one. The disk has a hot two-temperature configuration even without the assumption that instabilities in the disk drive the cold disk to this stage (which has been doubted in the past). Moreover, the spectrum from the transition zone matches well with the observed X-ray spectrum of Cygnus X-1 and variations in the magnetic field can account for the two X-ray states. We conclude from this new self-consistent model that the soft X-ray photons observed arise from the cold disk, the X-ray continuum is produced in the transition zone, while the γ-rays and associated phenomena (like the e⁺e⁻ line and the radio jets) are due to the inner hot disk.
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Tian, Jia. "Black Hole Microstates & Integrable Deformation in String Theory." Thesis, State University of New York at Albany, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10974293.
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In this thesis, we study microstate geometries of black holes in string theory and explore several aspects of integrabile Conformal Field Theories (CFTs). The first goal of this thesis is to get insights into physics of black holes by constructing a large new family of regular geometries that would account for the Bekenstein--Hawking entropy. Several classes of such states have been found in the past, but the number of known solutions is not sufficient to fully account for the entropy of macroscopic black holes. In this thesis we construct a large new family of regular microstate geometries and identify a new superposition principle for them. This feature stems from a hidden linear structure of equations governing our geometries, and it makes the dynamical system solvable or integrable. The second goal of this thesis is to explore the space of integrable string theories. Being analytically solvable, such models lead to important insights into the structure of strongly--coupled systems. While there is no algorithmic procedure for finding new integrable theories, in certain cases one can promote isolated examples into continuous families of solvable systems by performing so--called $\eta$-- and $\lambda$--deformations. In this thesis we combine the methods associated with these two deformations to construct multi--parameter families of integrable models and to explore analytical structure of the resulting theories. The third goal of this thesis is to study excitations of integrable backgrounds in string theory. The conventional approach to such analyses is based on separation of variables associated with continuous geometric symmetries, but it breaks down for the deformed models since all such symmetries are lost. Nevertheless, in this thesis we completely determine the spectra of scalar fields on several $\lambda$--deformed backgrounds by combining algebraic and group-theoretic methods.
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Olum, Ken D. "Vacuum-bounded states and the entropy of black hole evaporation." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43359.
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Festuccia, Guido Nicola Innocenzo. "Black hole singularities in the framework of gauge/string duality." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/45421.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.Includes bibliographical references (p. 201-209).
In this dissertation black hole singularities are studied using the AdS/CFT correspondence. These singularities show up in the CFT in the behavior of finite-temperature correlation functions. A direct relation is established between space-like geodesics in the bulk and momentum space Wightman functions of CFT operators of large dimensions. This allows to probe the regions inside the horizon and near the singularity using the CFT. Information about the black hole singularity is encoded in the exponential falloff of finite-temperature correlators at large imaginary frequency. We also find a UV/UV connection that governs physics inside the horizon. For the case the bulk theory lives in 5 dimensions the dual theory is an SU(N) Yang-Mills theory on a sphere, a bounded many-body system. The signatures of the singularity we found are only present as N -+ oo. To elucidate the emergence of the singularity in the gauge theory we further study the large N limit. We argue that in the high temperature phase the theory is intrinsically non-perturbative in the large N limit. At any nonzero value of the 't Hooft coupling A, an exponentially large (in N2) number of free theory states of wide energy range (or order N) mix under the interaction. As a result the planar perturbation theory breaks down. We argue that an arrow of time emerges in the gauge theory and the dual string configuration should be interpreted as a stringy black hole.
by Guido Nicola Innocenzo Festuccia.
Ph.D.
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Dai, De-Chang. "Modified Gravity in Cosmology and Fundamental Particle Physics." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1207065832.
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Hampton, Shaun David. "Understanding Black Hole Formation in String Theory." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531949063908224.
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Hambli, Noureddine. "Black hole evaporation and the role of ultrashort distances." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28457.
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The role played by ultrahigh frequencies or ultrashort distances in the usual derivation of the Hawking effect is discussed. We demonstrate the robustness of Hawking's prediction of black-hole evaporation, by carrying out an explicit calculation, in which short-distance physics is explicitly regularized using the Pauli-Villars regularization scheme. We find that short-distance effects due to physics at small distance scales, 1/$ Lambda gg 1/T sb{H}$, where 1/$ Lambda$ is a covariantly chosen short-distance cutoff, can only contribute to the Hawking flux an amount that is exponentially suppressed by the large ratio $ Lambda$/$T sb{H}$. We argue further that this behavior is not specific to our choice of regularization, but is a generic feature of any covariant short-distance regularization. We do so by showing that no possible covariant and local counterterm exists which can contribute to the Hawking flux at late times far from the hole.
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Miller, Jon Matthew 1975. "X-ray spectroscopic and timing studies of galactic black hole binaries." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29935.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2002.Includes bibliographical references (p. 183).
In rare cases, optical observations of Galactic binary star systems which are bright in the X-ray portion of the electromagnetic spectrum dynamically constrain the mass of one component to be well above theoretical limits for a neutron star. These systems - and systems with similar X-ray properties - are classified as black hole binaries. In this thesis, I report on observations of black hole binaries made with satellite observatories in the X-ray band. The region closest to the black hole is revealed in X-rays due to the viscous heating of matter that is accreted from the companion star. X-ray observations of these systems may therefore reveal General Relativistic effects. A fundamental and testable prediction of General Relativity is that matter may orbit more closely around black holes with significant angular momentum. I have investigated the possibility of black hole "spin" and the geometry of accretion flows in these systems using X-ray continuum spectroscopy, fast variability studies, and the shape of iron fluorescent emission lines in this band. I present evidence for black hole spin in XTE J1550-564, XTE J1650-500, and XTE J1748-248. Spin is not required by high-resolution spectral analysis of the archetypical Galactic black hole - Cygnus X-1 but a thermal accretion disk plus hot corona geometry is confirmed. Studies of XTE J1118+480 and GRS 1758-258 at low X-ray luminosity reveal that models for radiatively-inefficient accretion do not satisfactorily describe the geometry in these systems.
y Jon Matthew Miller.
Ph.D.
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Rutledge, Robert Edward. "An observational study of astrophysical black hole candidatesand gamma ray bursts." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/43313.
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Giguere, Alexis. "Primordial black hole seeding from hybrid inflation : the direct integration approach." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/88905.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (page 45).
We examine the notion that supermassive black holes at the centre of galaxies, such as the Milky Way, could have been seeded in the early universe by the mechanisms of hybrid inflation. Using luminosity data, we estimate the current density of supermassive black hole. We develop the formalism of the dierct integration method in hybrid inflation and obtain a power spectrum, which we try to relate to the literature. Our results do not directly show the plausibility of seeding supermassive black holes, but the shape of the power spectrum suggests that further work might yield positive results.
by Alexis Giguere.
S.B.
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Martínez, Montero Marina. "Studies of Black Hole Horizons." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/396271.
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This thesis has focused entirely on classical and thermodynamical aspects of black hole physics. We have developed four different projects involving different kinds of black holes.
1 BLACK BRANES IN A BOX
Neutral black branes with extended horizons are dynamically unstable to long wavelength perturbations along their horizons; this instability is known as the Gregory-Laflamme instability. In some regimes, the dynamics of black branes can be captured by an effective hydrodynamic description. We have studied the effective hydrodynamics of neutral black branes inside a cylindrical cavity to investigate their dynamic and thermodynamic instabilities. We have used the size of the box as a control parameter for stability (smaller cavities increase rigidity and contribute to the stability of the solutions); we have ob¬served that both instabilities disappear at the same critical value of the cavity radius. We have discussed the Correlated Stability Conjecture, which relates thermodynamic and dynamic instabilities in these objects and we have argued that its correct interpretation is given by the Correlated Hydrodynamic Stability (CHS). The CHS relates the presence of unstable hydrodynamic modes to the local thermodynamic instability; this is transparent in our approach. In the effective fluid description we have computed the specific quantities that characterize the fluid. Finally we have studied the system close to the critical point at which the instability disappears and we have obtained that the wave number that marks the onset of the instability vanishes with a critical behaviour ruled by a critical exponent of 1/2.
2 BLACK STRING FLOW
We have constructed an event horizon describing a heat flow, that remains constant in time, between to asymptotic regions at constant temperature. This horizon is the smooth interpolation between the horizon of a black string and a planar acceleration horizon. This was the first exact description of a flowing horizon connecting a stringlike horizon with a planar one (this can also be an infinitely big spherical black hole); the construction is valid for any number of dimensions greater than four. We obtained the horizon generators as well as the exact geometry and we showed that this horizon resembles that of flowing funnels. We computed a surface gravity that approaches on one end, the black string's surface gravity, and on the other, the infinite black hole's surface gravity which is 0. We also computed the expansion associated to the horizon generators and it vanishes in both asymptotic regions; thus reflecting the property that the black string flow horizon interpolates between two asymptotic horizons, each of which is asymptotically in equilibrium at different temperature. This construction shows that stationary black holes with non-killing horizons are possible with non-AdS asymptotics.
3 BUMPY BLACK HOLES
We have constructed numerically three new families of stationary black holes with a single angular momentum. These black holes have spherical topology but they differ from the Myers Perry solution (higher dimensional generalisation of Kerr solution) in that the radius of the sphere transverse to rotation varies non-monotonically with the polar angle. We have seen that half of these solutions connect, in the space of solutions, the Myers Perry family with other families featuring non-spherical topology such as the black ring, the black saturn, etc. We found strong evidence for the presence of cones in the horizons of solutions close to the topological transition in solution space. The other half of the solutions spread widely in the rotation plane and develop a singularity along their equator. These probably do not connect to other stationary black hole branches. We have also studied stability properties of all branches.
4 BLACK HOLE MERGER
We have described in an exact analytic way the event horizon of a black hole merger in the extreme mass ratio (EMR) limit; we have done it for four and five dimensions. Curiously numerical computation in which the ratio of the masses is large are difficult and not very well studied. We hope our exact result can serve as check/guide for future results in the area. We constructed the event horizon of this dynamical process by computing its null generators. We extracted a number of parameters that characterise the merger. We identified the line of caustics, the critical radius at which both horizons touch, the big horizon relaxation timescale among other things. We showed that our hypersurface describes all possible mergers, in the EMR limit, for which the small black hole is non-rotating. Finally we analysed the instants shortly before and after the pinch-on and found evidence for critical behaviour in the forming of the cusp and in the initial growth of the throat.Esta tesis está enmarcada en el campo de los agujeros negros. En ella se han realizado cuatro proyectos que involucran diferentes tipos de agujeros negros. 1 BRANAS NEGRAS Hemos estudiado el sistema de una brana dentro de una cavidad cilíndrica con condiciones de Dirichlet para investigar la relación entre las inestabilidades dinámicas y termodinámicas presentes en la brana. Hemos empleado las técnicas de la teoría efectiva de worldvolumes para tiranas; en esta teoría la descripción del sistema (en algunas condiciones) se da a través de variables y ecuaciones hidrodinámicas. Hemos estudiado el cambio de la inestabilidad de Gregory-Laflamme al variar el radio de la caja. Hemos identificado el radio crítico que estabiliza las soluciones y el comportamiento crítico de la inestabilidad en ese punto. 2 AGUJEROS NEGROS QUE FLUYEN Hemos construido un horizonte de sucesos que describe un flujo de calor, constante en el tiempo, entre dos regiones asintóticas a temperatura constante. Este horizonte es la interpolación entre el horizonte de una cuerda negra y un horizonte planar. La cuerda negra tiene cierta temperatura y el horizonte planar, en este caso, está a temperatura cero. La construcción se ha hecho en espacio asintóticamente plano, mostrando así que una constante cosmológica negativa no es estrictamente necesaria para la existencia de agujeros negros estacionarios con que no son de Killing. 3 AGUJEROS NEGROS BUMPY Hemos construido numéricamente tres familias nuevas de agujeros negros estacionarios con un solo momento angular en seis dimensiones. Estos agujeros tienen topología esférica pero el radio de la esfera transversa a la rotación varía de manera no monótona a lo largo del ángulo polar. La mitad de estas soluciones conectan a la familia de Myers Perry con otras de topología no esférica como el anillo negro o el saturno negro, etc. La otra mitad, se extienden mucho en el plano de rotación y acaban por tener una singularidad localizada en el ecuador. 4 FUSIÓN DE AGUJEROS NEGROS Para el caso en que las masas de dos agujeros negros difieran mucho una de la otra hemos mostrado que una descripción analítica del proceso de fusión de dos agujeros negros es posible. Hemos obtenido los rayos de luz que generan el horizonte de sucesos de una colisión de agujeros negros en el límite de razón de masas extremas. Extraemos propiedades importantes y damos una caracterización muy completa del proceso de fusión.
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Chong, Zhiwei. "Anti-de Sitter black holes in supergravity." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1837.
Full text
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Senturk, Cetin. "Black Hole Collisions At The Speed Of Light." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611479/index.pdf.
Full textAbstract:
The main purpose of this work is to study the collision of two black holes and the energy
loss due to the gravitational waves emitted during this collision in the framework of general
relativity. For this purpose we first study plane wave geometries and their collisions. More
realistic collisions are the pp-wave collisions. As an analytic treatment of this problem, we
investigate the head-on collision of two ultra-relativistic black holes. Treating the problem
perturbatively, we extract the news function to compute how much energy is radiated in gravitational
waves during the process. We show that the news function vanishes for the solutions
obtained meaning that there is no mass-loss at the order of approximation.
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Löffler, Frank. "Numerical simulations of neutron star - black hole mergers." Phd thesis, Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2006/774/.
Full textAbstract:
Collisions of black holes and neutron stars, named mixed binaries in the following, are interesting because of at least two reasons. Firstly, it is expected that they emit a large amount of energy as gravitational waves, which could be measured by new detectors. The form of those waves is expected to carry information
about the internal structure of such systems. Secondly, collisions of such objects are the prime suspects of short gamma ray bursts. The exact mechanism for the energy emission is unknown so far.
In the past, Newtonian theory of gravitation and modifications to it were often used for numerical simulations of collisions of mixed binary systems. However, near to such objects, the gravitational forces are so strong, that the use of General Relativity is necessary for accurate predictions.
There are a lot of problems in general relativistic simulations. However, systems of two neutron stars and systems of two black holes have been studies extensively in the past and a lot of those problems have been solved. One of the remaining problems so far has been the use of hydrodynamic on excision boundaries. Inside excision regions, no evolution is carried out. Such regions are often used inside black holes to circumvent instabilities of the numerical methods near the singularity. Methods to handle hydrodynamics at such boundaries have been described and tests are shown in this work.
One important test and the first application of those methods has been the simulation of a collapsing neutron star to a black hole. The success of these simulations and in particular the performance of the excision methods was an important step towards simulations of mixed binaries.
Initial data are necessary for every numerical simulation. However, the creation of such initial data for general relativistic situations is in general very complicated. In this work it is shown how to obtain initial data for mixed binary systems using an already existing method for initial data of two black holes.
These initial data have been used for evolutions of such systems and problems encountered are discussed in this work. One of the problems are instabilities due to different methods, which could be solved by dissipation of appropriate strength. Another problem is the expected drift of the black hole towards the neutron star. It is shown, that this can be solved by using special gauge conditions, which prevent the black hole from moving on the computational grid.
The methods and simulations shown in this work are only the starting step for a much more detailed study of mixed binary system. Better methods, models and simulations with higher resolution and even better gauge conditions will be focus of future work.
It is expected that such detailed studies can give information about the emitted gravitational waves, which is important in view of the newly built gravitational wave detectors. In addition, these simulations could give insight into the processes responsible for short gamma ray bursts.
Zusammenstöße eines schwarzen Lochs und eines Neutronensterns, im Folgenden "gemischte Zusammenstöße" genannt, sind aus wenigstens zwei Gründen interessant. Erstens wird erwartet, dass dabei große Mengen Energie als Gravitationswellen freigesetzt werden und diese mit neuen Detektoren gemessen werden können. Die Form dieser Wellen verrät viel über die Beschaffenheit eines solchen Systems und stellt neben elektromagnetischen Wellen eine wichtige Informationsquelle dar. Zweitens sind Zusammenstöße von kompakten Objekten wie Neutronensternen und schwarze Löchern sehr wahrscheinlich die Ursache sogenannter kurzer Gammastrahlungsblitze. Deren genauer Mechanismus für die Umwandlung der gewaltigen Energiemengen, die bei diesen Blitzen ausgesandt werden, ist jedoch bisher unbekannt.
Computersimulationen von Zusammenstößen eines gemischten Systems wurden bisher oft unter Benutzung der Newtonschen Gravitationstheorie, bzw. Korrekturen dazu, durchgeführt. In der Nähe so kompakte Objekte wie schwarzer Löcher oder Neutronensterne ist jedoch die Gravitationswirkung so stark, dass Näherungen wie die erwähnten Korrekturen der Newtonschen Gravitationstheorie zu ungenau sind. Eine Benutzung der allgemeinen Relativitätstheorie ist daher für dieses Problem unumgänglich.
Die Probleme allgemein-relativistischer Simulationen sind vielfältig. Jedoch wurden Binärsysteme zweier schwarzer Löcher und zweier Neutronensterne schon eingehend untersucht, und so viele Probleme, die auch Simulationen gemischter Systeme betreffen, gelöst. Eins der bisher ausstehenden Probleme war die Behandlung der Hydrodynamik an Ausschneiderändern; Rändern zu Gebieten, die in der Zeitentwicklung der Simulation ignoriert werden. Solche Ränder werden zum Beispiel innerhalb eines schwarzen Lochs benutzt, um Instabilitäten des Programms in der Nähe der Singularität zu vermeiden. Methoden, solche Ränder zu behandeln wurden in der Arbeit entwickelt, getestet und gezeigt, dass sie verlässlich arbeiten.
Ein wichtiger Test für diese Methoden, der gleichzeitig der Gewinnung neuer Erkenntnisse diente, war deren Anwendung auf Simulationen von zu schwarzen Löchern kollabierenden, rotierenden Sternen. Der Erfolg, diese Simulationen ohne Probleme mit den erwähnten Methoden durchzuführen, war ein wichtiger Schritt zu Simulationen gemischter Binärsysteme.
Für Computersimulationen sind Anfangsdaten notwendig, die das gewünschte Problem beschreiben. Die Erstellung solcher Anfangsdaten ist jedoch unter Benutzung der allgemeinen Relativitätstheorie ausser in Spezialfällen sehr komplex. Wir zeigen, wie man einen schon vorhandenen Algorithmus für Anfangsdaten für zwei schwarze Löcher ändern kann, um Anfangsdaten für ein gemischtes Binärsystem zu erhalten.
Diese Anfangsdaten wurden für Simulationen eines gemischten Binärsystems benutzt. Während dieser Simulationen traten mehrere Probleme auf. Zwei dieser Probleme waren numerische Instabilitäten unterschiedlicher Herkunft. Beide konnten jedoch mit angepasst starker Dissipation (der künstliche Entnahme von hochfrequenter Energie aus dem System) unterdrückt werden. Ein weiteres Problem war die erwartete Bewegung des schwarzen Lochs in Richtung des Neutronensterns. Da ein Teil des Simulationsgebietes innerhalb des schwarzen Lochs ausgeschnitten wird und das verwendete Programm bewegte Ausschneidegebiete nicht behandeln kann, darf sich das schwarze Loch jedoch auf dem Gitter kaum bewegen. Wir haben dieses Problem durch eine an das Problem angepasste Eichbedingung gelöst, die auf Bewegungen des scheinbaren Horizons reagiert und die Position des schwarzen Lochs auf diese Weise nahezu konstant hält.
Die Methoden und Simulationen dieser Arbeit sind nur der Anfangspunkt einer ausführlichen Studie von Binärsystemen eines schwarzen Lochs und eines Neutronensterns. Bessere Methoden, Modelle und Simulationen mit höherer Auflösung und besser an das System angepassten Koordinaten werden Mittelpunkt zukünftiger Arbeit sein.
Es wird erwartet, dass solche detailierten Studien Erkenntnisse über die abgestrahlten Gravitationswellen liefern, die gerade in Hinblick auf die neuen Gravitationswellendetektoren wichtig sind. Weiterhin könnten diese Simulationen dabei helfen, die Prozesse, die kurze Gammastrahlungsblitze hervorrufen, und über die im Moment kaum etwas bekannt ist, aufzuklären.
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Ferreira, Hugo Ricardo Colaço. "Quantum field theory on rotating black hole spacetimes." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/29626/.
Full textAbstract:
This thesis is concerned with the development of a general method to compute renormalised local observables for quantum matter fields, in a given quantum state, on a rotating black hole spacetime. The rotating black hole may be surrounded by a Dirichlet mirror, if necessary, such that a regular, isometry-invariant vacuum state can be defined. We focus on the case of a massive scalar field on a (2+1)-dimensional rotating black hole, but the method can be extended to other types of matter fields and higher-dimensional rotating black holes. The Feynman propagator of the matter field in the regular, isometry-invariant state is written as a sum over mode solutions on the complex Riemannian section of the black hole. A Hadamard renormalisation procedure is implemented at the level of the Feynman propagator by expressing its singular part as a sum over mode solutions on the complex Riemannian section of rotating Minkowski spacetime. This allows us to explicitly renormalise local observables such as the vacuum polarisation of the quantum field. The method is applied to the vacuum polarisation of a real massive scalar field on a (2+1)-dimensional warped AdS3 black hole surrounded by a mirror. Selected numerical results are presented, demonstrating the numerical efficacy of the method. The existence of classical superradiance and the classical linear mode stability of the warped AdS3 black hole to massive scalar field perturbations are also analysed.
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Sobrinho, José Laurindo de Góis Nóbrega. "The possibility of primordial black hole direct detection." Doctoral thesis, Universidade da Madeira, 2011. http://hdl.handle.net/10400.13/235.
Full textAbstract:
This thesis explores the possibility of directly detecting blackbody emission from
Primordial Black Holes (PBHs). A PBH might form when a cosmological density
uctuation with wavenumber k, that was once stretched to scales much larger than
the Hubble radius during ination, reenters inside the Hubble radius at some later
epoch. By modeling these uctuations with a running{tilt power{law spectrum
(n(k) = n0 + a1(k)n1 + a2(k)n2 + a3(k)n3; n0 = 0:951; n1 = 0:055; n2 and n3
unknown) each pair (n2,n3) gives a di erent n(k) curve with a maximum value
(n+) located at some instant (t+). The (n+,t+) parameter space [(1:20,1023 s) to
(2:00,109 s)] has t+ = 1023 s{109 s and n+ = 1:20{2:00 in order to encompass the
formation of PBHs in the mass range 1015 g{1010M (from the ones exploding at
present to the most massive known). It was evenly sampled: n+ every 0.02; t+ every
order of magnitude. We thus have 41 33 = 1353 di erent cases. However, 820 of
these ( 61%) are excluded (because they would provide a PBH population large
enough to close the Universe) and we are left with 533 cases for further study.
Although only sub{stellar PBHs ( 1M ) are hot enough to be detected at large
distances we studied PBHs with 1015 g{1010M and determined how many might have formed and still exist in the Universe. Thus, for each of the 533 (n+,t+) pairs we determined the fraction of the Universe going into PBHs at each epoch ( ), the PBH density parameter (PBH), the PBH number density (nPBH), the total number of PBHs in the Universe (N), and the distance to the nearest one (d). As a
rst result, 14% of these (72 cases) give, at least, one PBH within the observable
Universe, one{third being sub{stellar and the remaining evenly spliting into stellar,
intermediate mass and supermassive. Secondly, we found that the nearest stellar
mass PBH might be at 32 pc, while the nearest intermediate mass and supermassive
PBHs might be 100 and 1000 times farther, respectively.
Finally, for 6% of the cases (four in 72) we might have substellar mass PBHs within
1 pc. One of these cases implies a population of 105 PBHs, with a mass of 1018 g(similar to Halley's comet), within the Oort cloud, which means that the nearest
PBH might be as close as 103 AU. Such a PBH could be directly detected with a
probability of 1021 (cf. 1032 for low{energy neutrinos). We speculate in this
possibility.Pedro Manuel Edmond Reis da Silva Augusto
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Koppitz, Michael. "Numerical studies of Black Hole initial data." Phd thesis, Universität Potsdam, 2004. http://opus.kobv.de/ubp/volltexte/2005/134/.
Full textAbstract:
Diese Doktorarbeit behandelt neue Methoden der numerischen Evolution von Systemen mit binären Schwarzen Löchern. Wir analysieren und vergleichen Evolutionen von verschiedenen physikalisch motivierten Anfangsdaten und zeigen Resultate der ersten Evolution von so genannten 'Thin Sandwich' Daten, die von der Gruppe in Meudon entwickelt wurden. Zum ersten Mal wurden zwei verschiedene Anfangsdaten anhand von dreidimensionalen Evolutionen verglichen: die Puncture-Daten und die Thin-Sandwich Daten. Diese zwei Datentypen wurden im Hinblick auf die physikalischen Eigenschaften während der Evolution verglichen.
Die Evolutionen zeigen, dass die Meudon Daten im Vergleich zu Puncture Daten wesentlich mehr Zeit benötigen bevor sie kollidieren. Dies deutet auf eine bessere Abschätzung der Parameter hin. Die Kollisionszeiten der numerischen Evolutionen sind konsistent mit unabhängigen Schätzungen basierend auf Post-Newtonschen Näherungen die vorhersagen, dass die Schwarzen Löcher ca. 60% eines Orbits rotieren bevor sie kollidieren.
This thesis presents new approaches to evolutions of binary black hole systems in numerical relativity. We analyze and compare evolutions from various physically motivated initial data sets, in particular presenting the first evolutions of Thin Sandwich data generated by the Meudon group.
For the first time two different quasi-circular orbit initial data sequences are compared through fully 3d numerical evolutions: Puncture data and Thin Sandwich data (TSD) based on a helical killing vector ansatz. The two different sets are compared in terms of the physical quantities that can be measured from the numerical data, and in terms of their evolutionary behavior.
The evolutions demonstrate that for the latter, "Meudon" datasets, the black holes do in fact orbit for a longer amount of time before they merge, in comparison with Puncture data from the same separation. This indicates they are potentially better estimates of quasi-circular orbit parameters. The merger times resulting from the numerical simulations are consistent with independent Post-Newtonian estimates that the final plunge phase of a black hole inspiral should take 60% of an orbit.
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Licht, David. "Effective Dynamics of Black Hole Horizons." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/671802.
Full textAbstract:
In this thesis we present a new aspect pertaining to the effective field theory of general relativity in the limit of a large number D of dimensions. We demonstrate that the theory initially developed to capture the physics of asymptotically flat branes also contains a new family of localized solutions that can be identified with higher dimensional black holes such as the Schwarzschild-Thangerlini or the Myers-Perry black holes in the limit of a large number of spacetime dimensions. Using this technique we have explored several new aspects of these black hole solutions.
We show that the effective large D equations for the asymptotically flat brane also contain an analytic solution that is a gaussian blob (with the same topology as the flat membrane). The blob actually corresponds to a magnification of the geometry near the cap (north-pole) of the black hole. We calculate their (slow) quasi-normal spectrum, which captures the stability of Schwarzschild black holes and also the instability of ultraspinning Myers-Perry black holes.
Additionally we find novel class of rotating black bar solutions, that appear as stationary objects in the effective theory since they can not radiate gravitational waves which are decoupled from the effective theory.
We describe a method that allows to construct (Maxwell) charged solutions form every non- charged solution that the large D theory contains. Using this method we construct charged and rotating black holes in the Einstein-Maxwell theory.
Furthermore we explore the solutions that branch of from the (ultra-spinning) Myers-Perry (MP)
black hole and the non-linear extensions of the zero-modes of the analytically known black bar.
We study the evolution of higher dimensional black hole collisions by solving numerically the effective equations of motion. We demonstrate that in these collisions it is possible to form black holes with elongated horizons such as black bars and dumbbells. At high enough angular momentum the black bars and dumbbells can be so elongated that they are susceptible to a Greggory-Laflamme type instability, that leads to the a pinch off of the horizon towards a naked singularity. Accordingly this demonstrates a novel example of a violation of weak cosmic censorship in the quintessential process of general relativity: the collision of black holes.
Furthermore we study the evolution and decay of ultraspinning MP black holes, and observe remarkably rich structure in the intermediate states of the decay.
Lastly, we study how entropy production and irreversibility appear in the large D effective theory. With this tool we study how black hole entropy is generated in several highly dynamical processes, such as the fusion of black holes and the fission of unstable solutions into multiple black holes. We find the black hole fusion is highly irreversible, while fission which follows the decay of unstable black strings generates much less entropy. Additionally we describe how in processes that contain fusion and fission the intermediate state is quasi-thermalized.En esta tesis hemos presentado un nuevo aspecto perteneciente a la teoría efectiva de la relatividad general en el límite de un gran número de dimensiones. Hemos demostrado que la teoría desarrollada inicialmente para capturar la física de las branas asintóticamente planas también contiene una nueva familia de soluciones localizadas que pueden ser identificadas con agujeros negros de dimensiones más altas como los agujeros negros de Schwarzschild- Thangerlini o de Myers-Perry en el límite de gran D. Usando esta técnica hemos explorado varios aspectos nuevos de dichos agujeros negros. Encontramos una nueva clase de soluciones de barras negras giratorias, que aparecen como objetos estacionarios en la teoría efectiva Describimos un método que permite construir soluciones cargadas a partir de cada solución no cargada. Usando este método construimos agujeros negros cargados y giratorios en la teoría de Einstein-Maxwell. Estudiamos la evolución de las colisiones de agujeros negros en dimensiones superiores usando las ecuaciones efectivas. Demostramos que en estas colisiones es posible formar agujeros negros con horizontes alargados como barras negras o con forma de mancuernas. Con un momento angular lo suficientemente alto, las barras negras pueden ser tan alargadas que son susceptibles a una inestabilidad tipo Greggory-Laflamme, que lleva a una rotura del horizonte y a una singularidad desnuda. Por consiguiente, esto demuestra un ejemplo novedoso de una violación de la hipótesis de 'cosmic censorship' (censura cósmica). Además estudiamos la evolución y el decaimiento de los agujeros negros MP ultraspinning, y observamos una estructura notablemente rica en los estados intermedios del decaimiento.
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Vinciguerra, Serena. "Studying neutron-star and black-hole binaries with gravitational-waves." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8159/.
Full textAbstract:
The revolutionary discoveries of the last few years have opened a new era of astronomy. With the detection of gravitational-waves, we now have the opportunity of investigating new phenomena, such as mergers of black-holes. Furthermore, multi-messenger observations now allow us to combine information from different channels, providing insight into the physics involved. With this rapid evolution and growth of the field, many challenges need to be faced. In this thesis we propose three data analysis strategies to efficiently study the coalescences of compact binaries. First we propose an algorithm to reduce the computational cost of Bayesian inference on gravitational-wave signals. Second we prove that machine-learning signal classification could enhance the significance of gravitational-wave candidates in unmodelled searches for transients. Finally we develop a tool, saprEMo, to predict the number of electromagnetic events, which according to a specific emission model, should be present in a particular survey.
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Valcárcel, Luis 1979. "Gravitational Lorentz violations in 5D black hole background : a numerical investigation." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80891.
Full textAbstract:
The warped braneworld picture introduced by Randall and Sundrum provides new ways of solving long-standing problems in physics, like the gauge hierarchy problem. If the warp factor is different for the time and space components of the metric, new effects may arise. We concentrate on this possibility and show that the speed of gravity may differ from that of electromagnetism, while Lorentz invariance is preserved for the standard model fields. A charged black hole in a 5 dimensional bulk provides the necessary background. Its properties are studied in detail to ensure correct embedding of the brane. Computation of the speed of gravity in this setup is done both perturbatively and numerically. The results are compared with experimental bounds to constrain the parameters of our scenario.
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Paci, Gregorio. "Black hole thermodynamics and boundary terms in teleparallel gravity." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23219/.
Full textAbstract:
Teleparallel equivalent of General Relativity is an alternative theory of gravity that describes gravitational interactions only in terms of spacetime torsion instead of curvature. This theory can also be nicely formulated as a gauge theory for the translation group. TEGR is believed to be equivalent to General Relativity since their corresponding actions are equal up to a boundary term B. However, boundary terms do affect black hole thermodynamics. So, one could expect to obtain different results concerning BH thermodynamics in TEGR. However, at least at the leading order, this turns out not to be the case. Indeed, in this work we compute entropy and energy of the Teleparallel equivalent of a Schwarzschild BH, and we find that these values agree with those obtained in GR. Also, we construct the TEGR analog of the Landau-Lifshitz energy-momentum pseudo-tensor, from which we obtain the total conserved energy of Teleparallel Schwarzschild BH. This allows us to confirm the previous results, reinforcing the equivalence of black hole thermodynamics in GR and TEGR at the leading order.
Upon quantization, however, higher-order terms are expected to show up and spoil this equivalence. Thus, we study as well one-loop corrections to the partition function. To this purpose, we employed heat kernel methods to calculate the one-loop divergences of the effective action of a scalar field minimally coupled to gravity in TEGR. We find that these divergences are the same as what one obtains in GR. Then, we give some hints on the analogous calculations for the gravitational sector of the theory. In particular, we find out the second-order differential operator relevant for the heat kernel method and we present a simple argument that seems to indicate that the one-loop divergences of quantum TEGR are the same as in quantum GR too. However, there is a possible shortcoming concerning 1-loop corrections since the needed counterterms are not expected to have all the symmetries of TEGR.
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Moscato, Emanuele. "Black hole microstates and holography in the D1D5 CFT." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/31856.
Full textAbstract:
In this thesis we exploit the setup of AdS3/CFT2 holography, and in particular the D1D5 two-dimensional CFT, to describe states dual to geometries relevant for the \fuzzball" proposal for the description of six-dimensional black hole microstates. Precise holographic dualities between CFT and bulk geometric objects are established and checked, both for 2 and 3-charge states. In particular, VEVs of CFT operators of small conformal dimension are checked to encode deviations from AdS3 geometry near the spacetime boundary. 4-point functions of the \heavy-heavy-light-light" type are also considered and matching is found between CFT and bulk computations via the usual AdS/CFT prescription, with the heavy states being dual to (simple) microstate geometries. In this context, the issue of the presence of spurious singularities at leading order in the large N limit is assessed and cancellations are found even without considering sub-leading corrections, at the cost of considering the full detail of the D1D5 CFT (i.e. including the Virasoro blocks of operators of small dimension charged under the internal SU(2)L SU(2)R R-symmetry group). Finally, more complicated 4-point functions, involving operators in the twisted sector of the CFT, are computed and the results are checked against known results in the literature with the aim of verifying the robustness of the (new) techniques used. Supersymmetric Ward identities are also derived, and checked for some cases, between correlators written in terms of bosons and in terms of fermions.
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Hansen, James Michael. "Applications of AdS-CFT to problems in black hole physics and hydrodynamics." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1930286641&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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FRANZIN, EDGARDO. "Aspects of Black Hole Physics: Scalar Sources, Holography and Gravitational Wave Emission." Doctoral thesis, Università degli Studi di Cagliari, 2017. http://hdl.handle.net/11584/248734.
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We investigate several aspects of black hole physics.
First, we consider models of gravity minimally coupled to scalar fields. We derive a new class of asymptotically flat black holes sourced by a non-trivial asymptotically massless scalar field; we discuss their relationship with known solutions and standard no-hair theorems and their thermodynamics. We derive exact neutral and charged brane solutions sourced by a scalar field with vanishing potential, which are conformal to the Lifshitz spacetime; we discuss the symmetries and their holographic application for hyperscaling violation; we also give a quite general classification of brane solutions sourced by scalar fields useful for holographic applications. We study an inflationary model inspired by the domain wall/cosmology correspondence in which inflation is driven by a scalar with a two-exponential potential; we derive its phenomenological consequences in the slow-roll approximation and compare its predictions with the Planck 2015 data.
Second, we investigate ultra-compact astrophysical objects which can act as black hole mimickers, in particular boson stars and wormholes. We discuss the existence and the stability of boson stars in higher dimensions and boson stars built with multiple scalars. We compute tidal Love numbers for various mimickers and discuss how to distinguish black holes from their possible mimickers with gravitational-wave data. We study the gravitational radiation emitted by a particle falling into an exotic compact object and show that the initial ringdown signal cannot be use distinguish between a black hole and a black hole mimicker.We investigate several aspects of black hole physics. First, we consider models of gravity minimally coupled to scalar fields. We derive a new class of asymptotically flat black holes sourced by a non-trivial asymptotically massless scalar field; we discuss their relationship with known solutions and standard no-hair theorems and their thermodynamics. We derive exact neutral and charged brane solutions sourced by a scalar field with vanishing potential, which are conformal to the Lifshitz spacetime; we discuss the symmetries and their holographic application for hyperscaling violation; we also give a quite general classification of brane solutions sourced by scalar fields useful for holographic applications. We study an inflationary model inspired by the domain wall/cosmology correspondence in which inflation is driven by a scalar with a two-exponential potential; we derive its phenomenological consequences in the slow-roll approximation and compare its predictions with the Planck 2015 data. Second, we investigate ultra-compact astrophysical objects which can act as black hole mimickers, in particular boson stars and wormholes. We discuss the existence and the stability of boson stars in higher dimensions and boson stars built with multiple scalars. We compute tidal Love numbers for various mimickers and discuss how to distinguish black holes from their possible mimickers with gravitational-wave data. We study the gravitational radiation emitted by a particle falling into an exotic compact object and show that the initial ringdown signal cannot be use distinguish between a black hole and a black hole mimicker.
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MEDA, PAOLO. "On the Applications of Semiclassical Gravity in Cosmology and Black Hole Physics." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1087070.
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The subject of this Ph.D thesis is the study of the propagation of a free quantum scalar matter field over a classical curved spacetime in the realms of Cosmology and Black Hole Physics. It gathers the original research activity of the author in the framework of Semiclassical Gravity and Quantum Field Theory in Curved Spacetimes.
In a joint work with N. Pinamonti and D. Siemssen, the author shows the existence and uniqueness of local solutions of the semiclassical Einstein equations in cosmological spacetimes, driven by a free quantum massive scalar field arbitrarily coupled with the background curvature. The remarkable result of the work is to show that the source of regularity issues, which prevents to solve the semiclassical problem directly, is an unbounded operator hidden in the expectation value of the quantum stress-energy. However, this operator admits a more regular inverse, which also respects causality. Thus, the application of its inversion formula to the semiclassical equations allows to formulate a well-posed initial-value problem for local solutions in a small interval of time.
In collaboration with N. Pinamonti, S. Roncallo, and N. Zanghì, the semiclassical approach to gravity is applied in the framework of four-dimensional spherically symmetric black holes, which are characterized by dynamical future, outer, trapping horizons. It is shown that the trace anomaly of the quantum stress-energy tensor for a massless, conformally coupled scalar field can be the source of black hole evaporation, after assuming vacuum-like initial conditions in the past and an auxiliary quantum energy condition outside the horizon. As an example, the rate of evaporation induced by the trace anomaly is explicitly evaluated in the Vaidya spacetime.
Finally, in a joint paper with N. Pinamonti, the author studies the problem of stability of semiclassical solutions with higher-order derivative terms in a toy-model, consisting of a quantum scalar field in interaction with a classical scalar field. This toy-model mimics also the evolution induced by semiclassical Einstein equations in physically relevant backgrounds, such as cosmological spacetimes. The main result states that, if the quantum field is massive, then the back-reaction can restore stability on the classical background for wide choices of the renormalization constants, because linear perturbations with past compact spatial support decay polynomially in
time at large times.
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Onken, Christopher Alan. "Measurement of black hole masses in active Galactic Nuclei." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1125427208.
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Ukwatta, T. N., K. Hurley, J. H. MacGibbon, D. S. Svinkin, R. L. Aptekar, S. V. Golenetskii, D. D. Frederiks, et al. "INVESTIGATION OF PRIMORDIAL BLACK HOLE BURSTS USING INTERPLANETARY NETWORK GAMMA-RAY BURSTS." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621378.
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The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating primordial black holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the distance to GRBs using detections from widely separated, non-imaging spacecraft. This method can determine the actual distance to the burst if it is local. We applied this method to constrain distances to a sample of 36 short-duration GRBs detected by the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 10(13)-10(18) cm (7-10(5) au) range, which are consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Assuming that these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.
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Potter, William J. "Black hole jets, accretion discs and dark energy." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:e286380b-f2ab-4def-bcc4-32c191a3d76d.
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Black hole jets and accretion discs are the most extreme objects in modern astrophysics whilst dark energy is undoubtedly the most mysterious. This thesis focuses on understanding these three topics. The majority of this thesis is dedicated to investigating the structure and properties of black hole jets by modelling their emission. I develop an inhomogeneous jet model with a magnetically dominated parabolic accelerating base, transitioning to a slowly decelerating conical jet, with a geometry set by radio observations of M87. This model is able to reproduce the simultaneous multiwavelength spectra of all 38 Fermi blazars with redshifts in unprecendented detail across all wavelengths. I constrain the synchrotron bright region of the jet to occur outside the BLR and dusty torus for FSRQs using the optically thick to thin synchrotron break. At these large distances their inverse-Compton emission originates from scattering CMB photons. I find an approximately linear relation between the jet power and the transition region radius where the jet first comes into equipartition, transitions from parabolic to conical and stops accelerating. The decreasing magnetic field strength and increasing bulk Lorentz factor with jet power are the physical reasons behind the blazar sequence. I calculate the conditions for instability in a thin accretion disc with an α parameter which depends on the magnetic Prandtl number, as suggested by MHD simulations. The global behaviour of the instability induces cyclic flaring in the inner regions of the disc, for parameters appropriate for X-ray binary systems, thereby offering a potential solution to a long standing problem. Finally, I calculate the effect of an interacting quintessence model of dark energy on cosmological observables. I find that a scalar-tensor type interaction in the dark sector results in an observable increase in the matter power spectrum and integrated Sachs-Wolfe effect at horizon scales.
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Anous, Tarek. "Explorations in de Sitter Space and Amorphous Black Hole Bound States in String Theory." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10874.
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This dissertation is split into two distinct halves. The first covers various calculations done in order gain insights on holography in de Sitter space. The dispersion relation of linear perturbations of empty de Sitter space are numerically computed as a function of the location of a hypersurface on which conformal Dirichlet boundary conditions are imposed. When the hypersurface is near the south pole, the dispersion relation is linear, whereas for a hypersurface near the cosmological horizon, it satisfies that of the incompressible Navier-Stokes equation. This result is shown to hold for non-linear perturbations. We also compute the thermodynamic stability of rotating black holes in \(dS_4\) as a function of their mass and angular momentum. We focus particularly on the rotating Nariai geometry, which is a near horizon limit of the rotating black hole as the outer and cosmological horizons tend towards each other. We study massless scalar fields in these backgrounds and obtain their quasinormal mode spectrum explicitly. We uncover an interesting structure in their two-point functions, namely that they resemble thermal Green's functions of a two-dimensional conformal field theory. The second half of this dissertation deals with the study of multicentered black holes in string theory and their finite temperature extensions. We show that there exist finite temperature single-centered solutions in \(\mathcal{N}=2\) supergravity in asymptotically flat space that admit bound states with BPS probe particles. We compute the existence regions of these bound states as well as their dependence on temperature. We embed these solutions in Fayet-Illiopoulos gauged supergravity and show that bound states persist in asymptotically \(AdS_4\) spacetimes. We make attempts to understand these disordered bound states as amorphous/glassy phases of the dual conformal field theory.Physics
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Vigeland, Sarah Jane. "Studies of strong-field gravity : testing the black hole hypothesis and investigating spin-curvature coupling." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77506.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 151-159).
Observations of gravitational systems agree well with the predictions of general relativity (GR); however, to date we have only tested gravity in the weak-field limit. In the next few years, observational advances may make it possible for us to observe motion in the strong field for the first time. This thesis is concerned with two probes of strong-field gravity: whether the spacetime of a black hole has the structure predicted by GR, and the effect of spin-curvature coupling on orbital motion in the large mass-ratio limit. The first two-thirds of this thesis develop a formalism for determining whether a candidate black hole is described by the Kerr metric, as predicted by GR for all black holes in vacuum. In the first chapter, we describe how to construct a "bumpy black hole," an object whose spacetime is almost, but not quite, the Kerr metric. We define perturbations to the mass and spin moments and relate the changes in the moments to changes in the orbital frequencies using canonical perturbation theory. In the second chapter, we extend the bumpy black hole formalism to include black holes in non-GR theories of gravity, which leads to additional functional degrees of freedom. The final chapter investigates the effects of spin-curvature coupling. For a small body with spin moving around a massive black hole, the spin of the small body couples to the background curvature, and its trajectory deviates from a geodesic. To date, there has been relatively little work that considers this effect except in the special cases of aligned spins and circular, equatorial orbits. We compute the perturbation to the trajectory and the spin precession due to spin-curvature coupling for generic orbits of Kerr and arbitrary initial spin orientations.
by Sarah Jane Vigeland.
Ph.D.
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Rodriguez, Leo L. "Black-hole/near-horizon-CFT duality and 4 dimensional classical spacetimes." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1172.
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In this thesis we accomplish two goals: We construct a two dimensional conformal field theory (CFT), in the form of a Liouville theory, in the near horizon limit for three and four dimensions black holes. The near horizon CFT assumes the two dimensional black hole solutions that were first introduced by Christensen and Fulling (1977 Phys. Rev. D 15 2088-104) and later expanded to a greater class of black holes via Robinson and Wilczek (2005 Phys. Rev. Lett. 95 011303). The two dimensions black holes admit a $Diff(S^1)$ or Witt subalgebra, which upon quantization in the horizon limit becomes Virasoro with calculable central charge. These charges and lowest Virasoro eigen-modes reproduce the correct Bekenstein-Hawking entropy of the four and three dimensions black holes via the Cardy formula (Bl"ote et al 1986 Phys. Rev. Lett. 56 742; Cardy 1986 Nucl. Phys. B 270 186). Furthermore, the two dimensions CFT's energy momentum tensor is anomalous, i.e. its trace is nonzero. However, In the horizon limit the energy momentum tensor becomes holomorphic equaling the Hawking flux of the four and three dimensions black holes. This encoding of both entropy and temperature provides a uniformity in the calculation of black hole thermodynamics and statistical quantities for the non local effective action approach.
We also show that the near horizon regime of a Kerr-Newman-$AdS$ ($KNAdS$) black hole, given by its two dimensional analogue a la Robinson and Wilczek, is asymptotically $AdS_2$ and dual to a one dimensional quantum conformal field theory (CFT). The $s$-wave contribution of the resulting CFT's energy-momentum-tensor together with the asymptotic symmetries, generate a centrally extended Virasoro algebra, whose central charge reproduces the Bekenstein-Hawking entropy via Cardy's Formula. Our derived central charge also agrees with the near extremal Kerr/CFT Correspondence in the appropriate limits. We also compute the Hawking temperature of the $KNAdS$ black hole by coupling its Robinson and Wilczek two dimensional analogue (RW2DA) to conformal matter.
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Koushiappas, Savvas Michael. "From supermassive black holes to supersymmetric dark matter." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1085673923.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xxi, 172 p.; also includes graphics (some col.) Includes bibliographical references (p. 162-172). Available online via OhioLINK's ETD Center
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Pacucci, Fabio. "The First Black Holes in the Cosmic Dark Ages." Doctoral thesis, Scuola Normale Superiore, 2016. http://hdl.handle.net/11384/86205.
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The main objective of the original work presented in this Thesis is to develop a theoretical framework to understand the growth, cosmological evolution and observational features of the first black holes, formed when the Universe was younger than ∼ 1Gyr.
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Wei, Dennis. "X-ray power density spectra of black hole binaries : a new deadtime model for the RXTE PCA." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36115.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2006.Includes bibliographical references (p. 97-100).
The power density spectrum is an essential tool for determining the frequency content of X-ray radiation from astronomical sources. For neutron star systems, power density spectra reveal coherent oscillations for those sources that are pulsars, while quasi-periodic oscillations over a wide range of frequencies (0.01 to 1300 Hz) are used to identify subclasses and to probe the details of accretion physics. For black hole binaries, the power density spectrum is useful in many important contexts: distinguishing black hole binaries from neutron star binaries, tracking the evolution of X-ray states, and understanding the dynamics of accretion disks, in particular the high-frequency oscillations that appear to be rooted in general relativity for strong gravitational fields. However, measurements of the power density spectrum are modified by the effects of deadtime in X-ray detectors. In this work, we focus on the Proportional Counter Array (PCA) instrument of the Rossi X-ray Timing Explorer (RXTE), an orbiting observatory that offers fast, microsecond-level time resolution and modest spectral resolution for celestial X-ray sources. We derive a new model for the effect of detector deadtime on measurements of the power density spectrum.
(cont.) The model treats in a unified manner the contributions from self-deadtime among selected events and interference from non-selected events. Using high-frequency power density spectra obtained from observations of X-ray sources, the new model is shown to be more accurate than existing approaches. The comparison between the model and the observations leads to a measurement of 8.83 s for the fundamental instrument deadtime timescale, which is dominated by the analog-to-digital conversion time. We additionally measure 59 jts and 137 /is for the Very Large Event deadtime related to observer-specified settings 1 and 2 respectively. Future refinements to the deadtimle model are discussed, such as corrections for highly variable sources and for individual X-ray energy bands.
(cont.) A preliminary comparison between power density spectra from black hole binaries and neutron star binaries is undertaken using the new deadtime model. While it may be possible to use high-frequency cut-offs in the power continuum to distinguish neutron star binaries from black hole binaries in the thermal and hard X-ray states, the comparison is inconclusive for black hole binaries in the steep power-law state. Since state definitions require considerations of X-ray spectral properties, the comparison results dispute a suggestion in the literature that accreting neutron stars and black holes can be distinguished on the basis of power density spectra alone.
by Dennis Wei.
S.B.
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Wittmer, Paul [Verfasser], and Carlo [Akademischer Betreuer] Ewerz. "Application of Black-Hole Physics to Vortex Dynamics in Superfluids / Paul Wittmer ; Betreuer: Carlo Ewerz." Heidelberg : Universitätsbibliothek Heidelberg, 2021. http://d-nb.info/1225484480/34.
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