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Author: Laleh Sadeghian Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 90
Book Description
This thesis includes two main projects. In the first part, we assess the feasibility of a recently suggested strong-field general relativity test, in which future observations of a hypothetical class of stars orbiting very close to the supermassive black hole at the center of our galaxy, known as Sgr A*, could provide tests of the so-called no-hair theorem of general relativity through the measurement of precessions of their orbital planes. By considering how a distribution of stars and stellar mass black holes in the central cluster would perturb the orbits of those hypothetical stars, we show that for stars within about 0.2 milliparsecs (about 6 light-hours) of the black hole, the relativistic precessions dominate, leaving a potential window for tests of no-hair theorems. Our results are in agreement with N-body simulation results. In the second part, we develop a fully general relativistic phase-space formulation to consider the effects of the Galactic center supermassive black hole Sgr A* on the dark-matter density profile and its applications in the indirect detection of dark matter. We find significant differences from the non-relativistic result of Gondolo and Silk (1999), including a higher density for the spike and a larger degree of central concentration. Having the dark matter profile density in the presence of the massive black hole, we calculate its perturbing effect on the orbital motions of stars in the Galactic center, and find that for the stars of interest, relativistic effects related to the hair on the black hole will dominate the effects of dark matter.
Author: Laleh Sadeghian Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 90
Book Description
This thesis includes two main projects. In the first part, we assess the feasibility of a recently suggested strong-field general relativity test, in which future observations of a hypothetical class of stars orbiting very close to the supermassive black hole at the center of our galaxy, known as Sgr A*, could provide tests of the so-called no-hair theorem of general relativity through the measurement of precessions of their orbital planes. By considering how a distribution of stars and stellar mass black holes in the central cluster would perturb the orbits of those hypothetical stars, we show that for stars within about 0.2 milliparsecs (about 6 light-hours) of the black hole, the relativistic precessions dominate, leaving a potential window for tests of no-hair theorems. Our results are in agreement with N-body simulation results. In the second part, we develop a fully general relativistic phase-space formulation to consider the effects of the Galactic center supermassive black hole Sgr A* on the dark-matter density profile and its applications in the indirect detection of dark matter. We find significant differences from the non-relativistic result of Gondolo and Silk (1999), including a higher density for the spike and a larger degree of central concentration. Having the dark matter profile density in the presence of the massive black hole, we calculate its perturbing effect on the orbital motions of stars in the Galactic center, and find that for the stars of interest, relativistic effects related to the hair on the black hole will dominate the effects of dark matter.
Author: National Research Council Publisher: National Academies Press ISBN: 0309157994 Category : Science Languages : en Pages : 324
Book Description
Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010's. Realizing these scientific opportunities is contingent upon maintaining and strengthening the foundations of the research enterprise including technological development, theory, computation and data handling, laboratory experiments, and human resources. New Worlds, New Horizons in Astronomy and Astrophysics proposes enhancing innovative but moderate-cost programs in space and on the ground that will enable the community to respond rapidly and flexibly to new scientific discoveries. The book recommends beginning construction on survey telescopes in space and on the ground to investigate the nature of dark energy, as well as the next generation of large ground-based giant optical telescopes and a new class of space-based gravitational observatory to observe the merging of distant black holes and precisely test theories of gravity. New Worlds, New Horizons in Astronomy and Astrophysics recommends a balanced and executable program that will support research surrounding the most profound questions about the cosmos. The discoveries ahead will facilitate the search for habitable planets, shed light on dark energy and dark matter, and aid our understanding of the history of the universe and how the earliest stars and galaxies formed. The book is a useful resource for agencies supporting the field of astronomy and astrophysics, the Congressional committees with jurisdiction over those agencies, the scientific community, and the public.
Author: Manuel Arca Sedda Publisher: Elsevier ISBN: 0323956378 Category : Science Languages : en Pages : 510
Book Description
Black Holes in the Era of Gravitational-Wave Astronomy provides a multidisciplinary, up-to-date view of the physics of black holes, along with an exhaustive overview of crucial open questions and recent advancements in the astrophysics of black holes in the wake of incredible advancements made in the last decade. It includes discussions on improvements in theoretical modeling and observational perspectives for black holes of all sizes, along with associated challenges. The book's structure and themes will enable an entwined understanding of black hole physics at all scales, thus avoiding the compartmentalized view that is typical of more specialized manuscripts and reviews.This book is a complete reference for scientists interested in a multidirectional approach to the study of black holes. It provides substantial discussions about the interplay of different types of black holes and gives professionals a heterogeneous and comprehensive overview of the astrophysics of black holes of all masses. Focuses on recent advances and future perspectives surrounding black holes, providing researchers with a clear view of cutting-edge research Offers readers a multidisciplinary, fresh view on black holes, discussing and reviewing the most recent advancements in theoretical, numerical and observational techniques put in place to detect black holes Provides a bridge among different black hole areas, fostering new collaborations among professionals working in different, but intrinsically interconnected fields
Author: M. Colpi Publisher: CRC Press ISBN: 1420012096 Category : Science Languages : en Pages : 482
Book Description
Black holes are among the most mysterious objects that the human mind has been capable of imagining. As pure mathematical constructions, they are tools for exploiting the fundamental laws of physics. As astronomical sources, they are part of our cosmic landscape, warping space-time, coupled to the large-scale properties and life cycle of their host
Author: Boyuan Liu (Ph. D. in astronomy) Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
We use semi-analytical models and cosmological hydrodynamic simulations to derive the imprints of dark matter physics on the first generation of stars, black holes and galaxies, which, combined with observational data, place constraints on the properties of dark matter. Inspired by the recent detection of gravitational waves, we further investigate the gravitational waves of the first star remnants as a promising probe for early star/structure formation and dark matter physics. Our results indicate that although the first stars only make up a tiny fraction (~ 10−5) of all stars (ever formed) in the Universe, a much higher fraction (~ 10−3 -0.1) of massive compact object mergers can originate from the first stars, which carry valuable information of the early Universe. Finally, we explore the effects of primordial black holes, which can make up all or part of dark matter, on first star formation, and discuss their implications on using gravitational waves as a direct probe of dark matter
Author: Ken Freeman Publisher: Springer Science & Business Media ISBN: 9780387276168 Category : Science Languages : en Pages : 180
Book Description
Written for the educated non-scientist and scientist alike, it spans a variety of scientific disciplines, from observational astronomy to particle physics. Concepts that the reader will encounter along the way are at the cutting edge of scientific research. However the themes are explained in such a way that no prior understanding of science beyond a high school education is necessary.
Author: J. Val Blain Publisher: Nova Publishers ISBN: 9781594542435 Category : Science Languages : en Pages : 272
Book Description
It is generally believed that most of the matter in the universe is dark, i.e. cannot be detected from the light which it emits (or fails to emit). Its presence is inferred indirectly from the motions of astronomical objects, specifically stellar, galactic, and galaxy cluster/supercluster observations. It is also required in order to enable gravity to amplify the small fluctuations in the cosmic microwave background enough to form the large-scale structures that we see in the universe today. For each of the stellar, galactic, and galaxy cluster/supercluster observations the basic principle is that if we measure velocities in some region, then there has to be enough mass there for gravity to stop all the objects flying apart. Dark matter has important consequences for the evolution of the Universe and the structure within it. According to general relativity, the Universe must conform to one of three possible types: open, flat, or closed. The total amount of mass and energy in the universe determines which of the three possibilities applies to the Universe. In the case of an open Universe, the total mass and energy density (denoted by the Greek letter Omega) is less than unity. If the Universe is closed, Omega is greater than unity. For the case where Omega is exactly equal to one the Universe is "flat". This book details leading-edge research from around the globe.
Author: Cosimo Bambi Publisher: Springer ISBN: 9811045240 Category : Science Languages : en Pages : 340
Book Description
This textbook introduces the current astrophysical observations of black holes, and discusses the leading techniques to study the strong gravity region around these objects with electromagnetic radiation. More importantly, it provides the basic tools for writing an astrophysical code and testing the Kerr paradigm. Astrophysical black holes are an ideal laboratory for testing strong gravity. According to general relativity, the spacetime geometry around these objects should be well described by the Kerr solution. The electromagnetic radiation emitted by the gas in the inner part of the accretion disk can probe the metric of the strong gravity region and test the Kerr black hole hypothesis. With exercises and examples in each chapter, as well as calculations and analytical details in the appendix, the book is especially useful to the beginners or graduate students who are familiar with general relativity while they do not have any background in astronomy or astrophysics.“/p>
Author: Robert M. Wald Publisher: University of Chicago Press ISBN: 9780226870359 Category : Science Languages : en Pages : 300
Book Description
A comprehensive summary of progress made during the past decade on the theory of black holes and relativistic stars, this collection includes discussion of structure and oscillations of relativistic stars, the use of gravitational radiation detectors, observational evidence for black holes, cosmic censorship, numerical work related to black hole collisions, the internal structure of black holes, black hole thermodynamics, information loss and other issues related to the quantum properties of black holes, and recent developments in the theory of black holes in the context of string theory. Volume contributors: Valeria Ferrari, John L. Friedman, James B. Hartle, Stephen W. Hawking, Gary T. Horowitz, Werner Israel, Roger Penrose, Martin J. Rees, Rafael D. Sorkin, Saul A. Teukolsky, Kip S. Thorne, and Robert M. Wald.
Author: Andrei M. Bykov Publisher: Springer ISBN: 9789402417333 Category : Science Languages : en Pages : 0
Book Description
Clusters of galaxies are large assemblies of galaxies, hot gas and dark matter bound together by gravity. Galaxy clusters are now one of the most important cosmological probes to test the standard cosmological models. Constraints on the Dark Energy equation of state from the cluster number density measurements, deviations from the Gaussian perturbation models, the Sunyaev-Zeldovich effect as well as the dark matter proles are among the issues to be studied with clusters. The baryonic composition of clusters is dominated by hot gas that is in quasi-hydrostatic equilibrium within the dark matter-dominated gravitational potential well of the cluster. The hot gas is visible through spatially extended thermal X-ray emission, and it has been studied extensively both for assessing its physical properties and as a tracer of the large-scale structure of the Universe. Magnetic fields as well as a number of non-thermal plasma processes play a role in clusters of galaxies as we observe from radioastronomical observations. The goal of this volume is to review these processes and to investigate how they are interlinked. Overall, these papers provide a timely and comprehensive review of the multi-wavelength observations and theoretical understanding of clusters of galaxies in the cosmological context. Thus, the volume will be particularly useful to postgraduate students and researchers active in various areas of astrophysics and space science. Originally published in Space Science Reviews in the Topical Collection "Clusters of Galaxies: Physics and Cosmology"
Author: Laleh Sadeghian
Author: Laleh Sadeghian
Author: National Research Council
Author: Manuel Arca Sedda
Author: M. Colpi
Author: Boyuan Liu (Ph. D. in astronomy)
Author: Ken Freeman
Author: J. Val Blain
Author: Cosimo Bambi
Author: Robert M. Wald
Author: Andrei M. Bykov