Download or read book Black Hole Accretion Dynamics in Numerical Simulations written by Kenneth B. Henisey and published by . This book was released on 2011 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Light curves from accreting black hole systems exhibit variability which has neither been conclusively explained by analytic models nor seen in numerical simulations of these flows. Until recently, these computational studies have uniformly assumed alignment between the angular momenta of a black hole and its accretion disk. In contrast, observational data suggests that these tilted configurations may exist in real astrophysical systems and theoretical work indicates that tilt is accompanied by disk eccentricity and warp capable of exciting trapped diskoseismological modes. This dissertation analyzes the spatial and temporal behavior of fluid in fully three-dimensional, general relativistic, magnetohydrodynamical simulations, the first of their kind, of both tilted and untilted black hole accretion flows. We uncover characteristically greater variability in tilted simulations at frequencies similar to those predicted by the formalism of trapped modes, but ultimately conclude that its spatial structure is inconsistent with a modal interpretation. We find instead that over-dense clumps orbiting on roughly Keplerian trajectories appear generically in our global simulations independent of tilt and that these blobs give rise to acoustic wakes inside and outside of their corotation radius. Our three dimensional analysis of the flow yields two additional results. First, we confirm the strongly asymmetric nature of the tilted configuration by further describing two previously identified standing shock structures in the background flow; second, we show that these shocks effectively amplify the blob-wake variability and thus explain the increased variability observed in our tilted datasets. Our identification of clumps, wakes, and wake-shock interactions in these tilted, fully general relativistic, magnetohydrodynamical simulations will certainly be relevant to those models which incorporate tilt as a way to explain the observed variability in black hole accretion flow.
Download or read book Numerical Simulation of Viscous Shocked Accretion Flows Around Black Holes written by Kinsuk Giri and published by Springer. This book was released on 2014-08-30 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work developed in this thesis addresses very important and relevant issues of accretion processes around black holes. Beginning by studying the time variation of the evolution of inviscid accretion discs around black holes and their properties, the author investigates the change of the pattern of the flows when the strength of the shear viscosity is varied and cooling is introduced. He succeeds to verify theoretical predictions of the so called Two Component Advective Flow (TCAF) solution of the accretion problem onto black holes through numerical simulations under different input parameters. TCAF solutions are found to be stable. And thus explanations of spectral and timing properties (including Quasi-Period Oscillations, QPOs) of galactic and extra-galactic black holes based on shocked TCAF models appear to have a firm foundation.
Download or read book Numerical Simulations of Black Hole Accretion written by Geoffrey Ryan and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Black Hole Gravitohydromagnetics written by Brian Punsly and published by Springer Science & Business Media. This book was released on 2008-12-15 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: Black hole gravitohydromagnetics (GHM) is developed from the rudiments to the frontiers of research in this book. GHM describes plasma interactions that combine the effects of gravity and a strong magnetic field, in the vicinity (ergosphere) of a rapidly rotating black hole. This topic was created in response to the astrophysical quest to understand the central engines of radio loud extragalactic radio sources. The theory describes a "torsional tug of war" between rotating ergospheric plasma and the distant asymptotic plasma that extracts the rotational inertia of the black hole. The recoil from the struggle between electromagnetic and gravitational forces near the event horizon is manifested as a powerful pair of magnetized particle beams (jets) that are ejected at nearly the speed of light. This second edition of the book is updated throughout and contains a completely new chapter discussing state of the art and results of numerical simulations of ergospheric disk jets occurring in magnetohydrodynamic accretion flows.
Download or read book Numerical Studies of Black Hole neutron Star Binaries written by Francois Foucart and published by . This book was released on 2011 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Black hole-neutron star mergers are extremely energetic events with the potential to generate gravitational waves detectable by ground-based detectors. They can also form massive, hot accretion discs around a remnant black hole, which could power short gamma-ray bursts. Due to the strength of the gravitational interactions around the time of merger, black hole-neutron star binaries can only be studied in a general relativistic framework -- and as we lack analytical solutions to Einstein's equations of general relativity in the case of binary systems, numerical simulations are required to determine their evolution. In this thesis, we study black hole-neutron star binaries using the SpEC code. We show how to efficiently and accurately determine the initial conditions for numerical simulations, and study the influence on the dynamics of black hole-neutron star mergers of both the equation of state of nuclear matter - which is unknown but could be constrained through observations of compact binaries - and the spin of the black hole. We find that the dynamics of mergers is strongly affected by the radius of the star: small stars are harder to disrupt, form lower-mass discs and emit waves longer (and at higher frequency) than large stars. The component of the black hole spin aligned with the orbital angular momentum of the binary also modifies the disk formation process: high spins let the star approach closer to the black hole without plunging into it, subjecting it to stronger tidal forces and making it easier for the star to disrupt and form a massive disk.
Download or read book Theory of Black Hole Accretion Discs written by Marek A. Abramowicz and published by Cambridge University Press. This book was released on 2010-08-26 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: This authoritative volume is the first to present a comprehensive and up-to-date review of our new understanding of accretion disks around black holes. Interest in black hole accretion disks has undergone a renaissance in recent years because of developments in three complementary areas: theoretical modeling of relativistic plasmas, numerical simulations with supercomputers, and observational tests now possible using new observatories such as the Japanese X-ray satellite, ASCAR. This volume presents review papers on all these topics from leading world authorities who gathered at an international conference in Reykjavik, Iceland. The authors are M. Abramowicz, P. Artymowicz, A. Brandenburg, G. Bjornsson, P. Charles, A. Fabian, J. Krolik, J.-P. Lasota, G. Madejski, R. Narayan, I. Novikov, J. Papaloizou, J. Poutanen, J. Pringle, M. Rees, E. Spiegel, R. Svensson, P. Witta. This timely volume provides an up-to-date review of the theory of black hole accretion disks for graduate students and researchers in astrophysics and theoretical physics.
Download or read book The Physics of Accretion onto Black Holes written by Maurizio Falanga and published by Springer. This book was released on 2014-10-28 with total page 483 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a comprehensive summary on the physical models and current theory of black hole accretion, growth and mergers, in both the supermassive and stellar-mass cases. This title reviews in-depth research on accretion on all scales, from galactic binaries to intermediate mass and supermassive black holes. Possible future directions of accretion are also discussed. The following main themes are covered: a historical perspective; physical models of accretion onto black holes of all masses; black hole fundamental parameters; and accretion, jets and outflows. An overview and outlook on the topic is also presented. This volume summarizes the status of the study of astrophysical black hole research and is aimed at astrophysicists and graduate students working in this field. Originally published in Space Science Reviews, Vol 183/1-4, 2014.
Download or read book General relativistic Magnetohydrodynamics Simulations of Black Hole Accretion Disks Dynamics and Radiative Properties written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Black Hole Accretion Disks written by 加藤正二 and published by Trans Pacific Press. This book was released on 1998-02 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Astrophysical Black Holes written by Francesco Haardt and published by Springer. This book was released on 2015-11-03 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on graduate school lectures in contemporary relativity and gravitational physics, this book gives a complete and unified picture of the present status of theoretical and observational properties of astrophysical black holes. The chapters are written by internationally recognized specialists. They cover general theoretical aspects of black hole astrophysics, the theory of accretion and ejection of gas and jets, stellar-sized black holes observed in the Milky Way, the formation and evolution of supermassive black holes in galactic centers and quasars as well as their influence on the dynamics in galactic nuclei. The final chapter addresses analytical relativity of black holes supporting theoretical understanding of the coalescence of black holes as well as being of great relevance in identifying gravitational wave signals. With its introductory chapters the book is aimed at advanced graduate and post-graduate students, but it will also be useful for specialists.
Download or read book Multidimensional Multiscale Dynamics of High energy Astrophysical Flows written by Sean Michael Couch and published by . This book was released on 2010 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrophysical flows have an enormous dynamic range of relevant length scales. The physics occurring on the smallest scales often influences the physics of the largest scales, and vice versa. I present a detailed study of the multiscale and multidimensional behavior of three high-energy astrophysical flows: jet-driven supernovae, massive black hole accretion, and current-driven instabilities in gamma-ray burst external shocks. Both theory and observations of core-collapse supernovae indicate these events are not spherically-symmetric; however, the observations are often modeled assuming a spherically-symmetric explosion. I present an in-depth exploration of the effects of aspherical explosions on the observational characteristics of supernovae. This is accomplished in large part by high-resolution, multidimensional numerical simulations of jet-driven supernovae. The existence of supermassive black holes in the centers of most large galaxies is a well-established fact in observational astronomy. How such black holes came to be so massive, however, is not well established. In this work, I discuss the implications of radiative feedback and multidimensional behavior on black hole accretion. I show that the accretion rate is drastically reduced relative to the Eddington rate, making it unlikely that stellar mass black holes could grow to supermassive black holes in less than a Hubble time. Finally, I discuss a mechanism by which magnetic field strength could be enhanced behind a gamma-ray burst external shock. This mechanism relies on a current-driven instability that would cause reorganization of the pre-shock plasma into clumps. Once shocked, these clumps generate vorticity in the post-shock plasma and ultimately enhance the magnetic energy via a relativistic dynamo process.
Download or read book Growing Black Holes Accretion in a Cosmological Context written by Andrea Merloni and published by Springer Science & Business Media. This book was released on 2005-04-25 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supermassive black holes are now believed to play an important role in the evolution of the Universe. Every respectable galaxy hosts in its center a black hole that appears to regulate the growth of the galaxy itself. In this book, leading experts in the field review the most recent theoretical and observational results on the following topics: - formation and growth of the first black holes in the Universe and their role in the formation and evolution of galaxies - the physics of black-hole accretion and the production of relativistic jets - binary black-hole mergers and gravitational radiation. Theoretical work is supplemented by the most recent exciting results from space and ground based observatories. This volume is useful research and reference tool for the entire astrophysical community.
Download or read book Novel Aspects of the Dynamics of Binary Black hole Mergers written by Philipp Mösta and published by . This book was released on 2011 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Accretion Power in Astrophysics written by Juhan Frank and published by Cambridge University Press. This book was released on 2002-01-17 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accretion Power in Astrophysics examines accretion as a source of energy in both binary star systems containing compact objects, and in active galactic nuclei. Assuming a basic knowledge of physics, the authors describe the physical processes at work in accretion discs and other accretion flows. The first three chapters explain why accretion is a source of energy, and then present the gas dynamics and plasma concepts necessary for astrophysical applications. The next three chapters then develop accretion in stellar systems, including accretion onto compact objects. Further chapters give extensive treatment of accretion in active galactic nuclei, and describe thick accretion discs. A new chapter discusses recently discovered accretion flow solutions. The third edition is greatly expanded and thoroughly updated. New material includes a detailed treatment of disc instabilities, irradiated discs, disc warping, and general accretion flows. The treatment is suitable for advanced undergraduates, graduate students and researchers.
Download or read book Relativistic Radiative Hydrodynamics Calculation of Accretion Flow Into Supermassive Black Hole written by Po Kin Leung and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The compact radio source Sagittarius A* (Sgr A*) is the nearest and most-intensively-studied supermassive black hole candidate. With a broadband spectrum which likely requires several emission mechanisms for explanation, and structure of innermost accretion flow not yet well constrained, the understanding of accretion into Sgr A* demands advances in both theories and computational calculation. To increase the understanding of Sgr A* in particular, and low-luminosity active galactic nuclei in general, we perform relativistic radiative transfer (RT) calculation with general relativistic magnetohydrodynamic (GRMHD) simulation of accretion flow simulation. We are able to use the models to constrain observational parameters of Sgr A*. We also compute the synchrotron emissivity and absorptivity from first principles, in order to verify improved approximate equations for the RT calculation. The code can handle a wide range of electron distributions, therefore the application is not limited to accretion disk simulation. In order to explain a feature in the observed flaring spectrum, we add nonthermal component to the electron distribution. We then perform relativistic Monte Carlo RT calculation of the disk model, and show that a small amount of power-law electron is enough to modify the spectral slope. Finally, we describe a recipe for performing relativistic polarized RT, which would allow a further study to constrain model parameters with polarization observations from Sgr A*.
Download or read book Black Holes IAU S238 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2007-07-30 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: IAU S238 report on the physics of black holes, by leading researchers in the field.
Download or read book Relativistic Hydrodynamics written by Luciano Rezzolla and published by OUP Oxford. This book was released on 2013-09-26 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: Relativistic hydrodynamics is a very successful theoretical framework to describe the dynamics of matter from scales as small as those of colliding elementary particles, up to the largest scales in the universe. This book provides an up-to-date, lively, and approachable introduction to the mathematical formalism, numerical techniques, and applications of relativistic hydrodynamics. The topic is typically covered either by very formal or by very phenomenological books, but is instead presented here in a form that will be appreciated both by students and researchers in the field. The topics covered in the book are the results of work carried out over the last 40 years, which can be found in rather technical research articles with dissimilar notations and styles. The book is not just a collection of scattered information, but a well-organized description of relativistic hydrodynamics, from the basic principles of statistical kinetic theory, down to the technical aspects of numerical methods devised for the solution of the equations, and over to the applications in modern physics and astrophysics. Numerous figures, diagrams, and a variety of exercises aid the material in the book. The most obvious applications of this work range from astrophysics (black holes, neutron stars, gamma-ray bursts, and active galaxies) to cosmology (early-universe hydrodynamics and phase transitions) and particle physics (heavy-ion collisions). It is often said that fluids are either seen as solutions of partial differential equations or as "wet". Fluids in this book are definitely wet, but the mathematical beauty of differential equations is not washed out.
