Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 56 for “"Compact Objects"”.
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Compact Objects In Relativistic Theories Of Gravity
… this dissertation we discuss several aspects of compact objects, i.e. neutron stars and black holes, in relativistic theories of gravity. We start by studying the role of nuclear physics (encoded in the so-called equation of state) in determining the properties of neutron stars in general …
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Modeling Compact Objects with Effective Field Theory
… developed a worldline Effective Field Theory of compact objects, by extending the model of spinning extended objects derived using the coset construction [1], from which one can derive the effective theory from symmetry principles. To massive spinning extended objects, we have added …
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Multiwavelength studies of accretion disks around compact objects
(cont.) to the XPS in SNR RCW 103. The multiple IR band measurements of 1E 1048.1-5937 provide marginal evidence for spectral flattening, and cannot rule out an accretion disk scenario for AXPs.
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PROBING THE NATURE OF COMPACT OBJECTS: SCATTERING, TIDES AND QUASINORMAL MODES
… the unique possibility to probe the nature of compact objects and gravitational dynamics. This dissertation investigates how the intrinsic properties of compact objects affect their dynamics and GW emission, using worldline effective field theories (WEFTs) and BH perturbation theory (BHPT), …
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Optical and near infrared observations of accretion processes in galactic compact objects
… optical and near-infrared observations of compact binary systems. The observations are used to refine the binary parameters of several Low Mass X-ray Binaries, and to better understand the accretion processes in these systems. Accretion is essential in the formation of stars, planets and …
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Gravitational collapse, compact objects and gravitational waves in General Relativity and modified gravity
… signatures. We analyse the formation of compact objects from core collapse simulations of stars in massive ST theories over the astrophysically plausible range of stellar progenitor masses and metallicities, as well as a large part of the parameter space of this class of modified theories …
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Black holes and how to find them : on the detection of compact objects at several scales
This dissertation is structured in four chapters. First, the reader is introduced to current detection methods for astrophysical black holes at different scales. The following three chapters correspond to different research projects regarding black hole detection. The second chapter presents the …
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Accreting Compact Objects in Technicolor: Multiwavelength Characterization of High Mass X-ray Binaries in the Local Group
… binaries (HMXBS) are systems that contain a compact object (neutron star or black hole) that accretes mass from a massive stellar companion. HMXBs are highly observable due to their bright X-ray luminosities, making them an observational window into the complex process of massive binary …
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Very old and very young compact objects : X-ray studies of galactic globular clusters and recent core-collapse supernovae
… Space Telescope and the Australia Telescope Compact Array, I make 12 optical identifications and one radio identification. Based on X-ray and optical properties of the identifications, I find 10 likely cataclysmic variables (CVs), 1-3 likely RS CVn or BY Dra systems, and 1 or 2 possible …
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Using novel spectral-timing techniques to probe the rapid variability of X-Ray Binaries
… the accretion disc and corona in accreting compact objects. In this thesis, I present the use of variability techniques to disentangle the different variable components of X-ray spectra. By examining correlated variability over a range of timescales, I identify for the first time evidence of …
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Experimental gravity with electromagnetic and gravitational waves
… can be used to elucidate the nature of compact objects and the fundamental properties of the material in their vicinity. Our ability to extract information about the underlying physics from observations of both electromagnetic and gravitational spectra depends on our understanding of the …
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Enhancing the detection and the reconstruction of gravitational-wave transients in the LIGO-Virgo-KAGRA data using weak assumptions on the astrophysical sources
… astrophysical signals interpreted as mergers of compact objects. These observations provide invaluable tests of the General Relativity and open a new era of astronomy, unveiling compact objects’ nature. The focus of the thesis is the detection and the characterization of GW transients with …
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Uncovering gravitational wave signatures of modified theories of gravity and exotic matter
… of modified theories gravity and exotic compact objects have been put forward to address experimental data, theoretical inconsistencies of the theory of general relativity, and merely human curiosity of `what if?'. In the pursuit of addressing all of the open questions, we now find …
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Numerical Modelling of the Dynamics and Gravitational Radiation of Compact Binaries in General Relativity
… big bang. Other examples are self gravitating compact objects such as black holes (BH) and the precise modelling neutron stars (NS). The gravitational waves from the inspirals and collisions of BHs and NSs can be measured by large interferometer experiments such as the Laser Interferometer …
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Simulations of Dynamic Relativistic Magnetospheres
… for studying the dynamic magnetospheres of compact objects. A detailed description of the code and several numerical test problems are given. I first apply the code to the aligned rotator problem, in which a star with a dipole magnetic field is set rotating about its magnetic axis. The …
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Chasing ancient demons : tools for measuring 21 cm fluctuations before reionization
… carry information on the first X-ray emitting compact objects and hot interstellar gas heated by the deaths of the first stars (ancient demons). First, we show that existing and planned interferometers are sensitive enough to place interesting constraints on the astrophysics of X-ray heating. …
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Acoustic classification of buried objects with mobile sonar platforms
… for the purpose of acoustically classifying compact objects on or below the seabed. The extension of existing strategies, including synthetic aperture sonar and conventional imaging, are explored within the context of the buried object problem. In particular, the need to employ low …
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Precursors in Gamma-ray Bursts Observed by Fermi
… collapses of massive stars and the mergers of compact objects, and are observed as bright flashes of gamma rays (prompt emission) followed by long-lived, fading emission (afterglow) across the electromagnetic spectrum. The instruments on the Fermi Gamma-ray Space Telescope provide excellent …
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Gravitational influences on magnetic field structure in accretion disks
Black holes and compact objects are often surrounded by structures known as accretion disks which consist of ionized plasma. Due to the immense forces present in the disk, interesting and complex magnetic field structures can be set up within the disk. The influence of gravity on these structures …
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