Electromagnetic Signatures of an Analytical Mini-disk Model of Supermassive Binary Black Hole Systems PDF Download
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Author: Kaitlyn Porter
Publisher:
ISBN:
Category : Black holes (Astronomy)
Languages : en
Pages : 0
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"Supermassive black holes (SMBHs) are thought to be located at the centers of most galactic nuclei. When galaxies merge they form supermassive black hole binary (SMBHB) systems and these central SMBHs will also merge at later times, producing gravitational waves (GWs). Galaxy mergers are gas rich environments and there is likely to be matter surrounding the binary system as well as accreting onto the individual black holes. Therefore, SMBHBs are potential sources of electromagnetic (EM) radiation. The EM signatures depend on gas dynamics, orbital dynamics, and radiation processes. The gas dynamics are governed by general relativistic magnetohydrodynamics in a time-dependent spacetime. Numerically solving the magnetohydrodynamic equation for a time-dependent binary spacetime is computationally expensive. Therefore, it is challenging to conduct a full exploration of the parameter space of these systems and the resulting EM signatures. We have developed an analytical accretion disk model for the mini-disks of a binary black hole system and produced images and light curves using a general relativistic ray-tracing code and a superimposed harmonic binary black hole metric. This analytical model greatly reduces the time and computational resources needed to explore these systems, while incorporating some key information from simulations. We present a parameter space exploration of the SMBHB system in which we have studied the dependence of the electromagnetic signatures on the spins of the black holes, their mass ratio, and their accretion rate."--Abstract.
Author: Kaitlyn Porter
Publisher:
ISBN:
Category : Black holes (Astronomy)
Languages : en
Pages : 0
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"Supermassive black holes (SMBHs) are thought to be located at the centers of most galactic nuclei. When galaxies merge they form supermassive black hole binary (SMBHB) systems and these central SMBHs will also merge at later times, producing gravitational waves (GWs). Galaxy mergers are gas rich environments and there is likely to be matter surrounding the binary system as well as accreting onto the individual black holes. Therefore, SMBHBs are potential sources of electromagnetic (EM) radiation. The EM signatures depend on gas dynamics, orbital dynamics, and radiation processes. The gas dynamics are governed by general relativistic magnetohydrodynamics in a time-dependent spacetime. Numerically solving the magnetohydrodynamic equation for a time-dependent binary spacetime is computationally expensive. Therefore, it is challenging to conduct a full exploration of the parameter space of these systems and the resulting EM signatures. We have developed an analytical accretion disk model for the mini-disks of a binary black hole system and produced images and light curves using a general relativistic ray-tracing code and a superimposed harmonic binary black hole metric. This analytical model greatly reduces the time and computational resources needed to explore these systems, while incorporating some key information from simulations. We present a parameter space exploration of the SMBHB system in which we have studied the dependence of the electromagnetic signatures on the spins of the black holes, their mass ratio, and their accretion rate."--Abstract.
Author: Takamitsu Tanaka
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Finally, we apply these solutions to model the electromagnetic emission of accretion disks around supermassive black hole binaries that may be detectable with precision pulsar timing.
Author: Philipp Mösta
Publisher:
ISBN:
Category :
Languages : en
Pages : 246
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Author: Dennis B. Bowen
Publisher:
ISBN:
Category : Black holes (Astronomy)
Languages : en
Pages : 125
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"Supermassive binary black holes (SMBBHs) represent an excellent candidate for future combined gravitational wave and electromagnetic astrophysics, commonly referred to as multimessenger astrophysics. While much is known about the gravitational wave signal of merging BBHs, little is known about the electromagnetic emission. Modeling the electromagnetic emission coincident with gravitational waves requires simulations of SMBBHs coupled to their astrophysical environment, particularly during the late stages of inspiral and merger. These simulations necessitate a broad range of physics including general relativity, magnetohydrodynamics, and radiation physics. In this Dissertation we present simulations of SMBBHs coupled to their astrophysical environment. We explore, for the first time, the gas dynamics in a relativistic binary black hole (BBH) system in which an accretion disk (a 'mini-disk') orbits each black hole. In addition to studying the structure and dynamics of the mini-disks, we present spectra from ray-tracing calculations of SMBBH accretion including mini-disks. Due to the immense computational burden of these simulations (millions of CPU hours per binary orbit), we restrict our study to equal-mass, non-spinning SMBBHs. Relativistic effects alter the dynamics of gas in this environment in several ways. Because the gravitational potential between the two black holes becomes shallower than in the Newtonian regime, the mini-disks stretch toward the L1 point and the amount of gas passing back and forth between the mini-disks increases sharply with decreasing binary separation. This \enquote{sloshing} is quasi-periodically modulated at 2 and 2.75 times the binary orbital frequency, corresponding to timescales of hours to days for SMBBHs. In addition, relativistic effects add an azimuthal m = 1 component to the tidally driven spiral waves in the disks that are purely m = 2 in Newtonian gravity; this component becomes dominant when the separation is
Author: Andrea Marie Derdzinski
Publisher:
ISBN:
Category :
Languages : en
Pages :
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With a suite of simulations varying these characteristics, we elucidate the sensitivity of the gas imprint and its detectability to mass ratio, disk viscosity, and Mach number. Since the characteristic imprint on the GW signal is strongly dependent on disk parameters, a LISA detection of a gas-embedded inspiral would probe the physics of AGN disks and migration. Finally, we explore an electromagnetic signature of a circumbinary disk produced in response to a massive black hole binary merger. With hydrodynamical simulations that resolve the vertical structure of a circumbinary disk, we show that the change in potential produced during the final coalescence of a binary can perturb the surrounding material, producing shocks above the disk midplane, and that this response depends on the disk temperature. This carries implications for the associated emission following the GW signal, which may produce non-thermal radiation that varies with disk properties.
Author: Brennan M. Ireland
Publisher:
ISBN:
Category : Black holes (Astronomy)
Languages : en
Pages : 165
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"Observations of black hole binaries via the emission of gravitational waves are one of the most exciting discoveries in physics in the past 50 years. The most generic black holes in nature are ones with spin, which may be misaligned with the orbital angular momentum of the binary, and also orbital eccentricity. This demands computationally inexpensive and accurate models of spinning binary black holes for hundreds of orbits as the binary inspirals. This dissertation is divided into two projects, both of which focus on binary black holes with spin. In the first project, I construct and present a new global, fully analytic, approximate spacetime which accurately describes the dynamics of nonprecessing, spinning black hole binaries during the inspiral phase of the relativistic merger process. This approximate solution of the vacuum Einstein's equations can be obtained by asymptotically matching perturbed Kerr solutions near the two black holes to a post-Newtonian metric valid far from the two black holes. This metric is then matched to a post-Minkowskian metric even farther out in the wave zone. The procedure of asymptotic matching is generalized to be valid to all times, instead of a small group of initial hypersurfaces discussed in previous works. I then re-examine the asymptotic matching in the case of precession of the spins, allowing for generically spinning black hole binary metrics. This metric is well suited for long term dynamical simulations of spinning black hole binary spacetimes prior to merger, such as studies of circumbinary gas accretion which requires hundreds of binary orbits. In the second project, I present a method for developing and calculating the gravitational waveforms from generically spinning, black hole binaries, with significant orbital eccentricity. I use the Lagrangian formulation of the post Newtonian equations of motion in the harmonic gauge for the generation of precessing, eccentric gravitational wave signatures. The equations of motion describing the black hole binary system are important to our understanding of fundamental relativity, for both the context of supermassive black holes as well as stellar mass systems. If gravitational wave measurements are able to measure a non-negligible eccentricity from the binary, this may point to a unique formation model through relativistic 3-body interactions in dense stellar fields, which will impart occasionally significant eccentricity. This provides insight into the formation history of the binary, and explicitly the last dynamical effect the binary experienced before merging."--Abstract.
Author:
Publisher:
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Category :
Languages : en
Pages : 35
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We report on the discovery of a supermassive binary black hole system in the radio galaxy 0402+379, with a projected separation between the two black holes of just 7.3 pc. This is the closest black hole pair yet found by more than two orders of magnitude. These results are based upon recent multi-frequency observations using the Very Long Baseline Array (VLBA) which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of 0402+379. Multiepoch observations from the VLBA also provide constraints on the total mass and dynamics of the system. Low spectral resolution spectroscopy using the Hobby-Eberly Telescope indicates two velocity systems with a combined mass of the two black holes of 1.5 108 M . The two nuclei appear stationary while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this system has implications for the number of close binary black holes that might be sources of gravitational radiation. Green Bank Telescope observations at 22 GHz to search for water masers in this interesting system are also presented.
Author: Vincent Mannings
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1470
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Click here for the online version of this book! This title, out of print in 2008, is now available free of charge, in it's entirety, online through the University of Arizona Press! Both a textbook and a status report for every facet of research into the formation of stars and planets, Protostars and Planets IV brings together 167 authors who report on the most significant advances in the field since the publication of the previous volume in 1993. Protostars and Planets IV reflects improvements in observational techniques and the availability of new facilities such as the Infrared Space Observatory, the refurbished Hubble Space Telescope, and the 10-m Keck telescopes. Advances in computer technology and modeling methods have benefited theoretical studies of molecular clouds, star formation, and jets and disks, while recent analyses of meteorites yield important insights into conditions and processes within our Sun's early protoplanetary disk. The 49 chapters describe context and progress for observational and theoretical studies of the structure, chemistry, and dynamics of molecular clouds; the collapse of cores and the formation of protostars; the formation and properties of young binary stars; the properties of winds, jets, and molecular outflows from young stellar objects; the evolution of circumstellar envelopes and disks; grain growth in disks and the formation of planets; and the properties of the early Solar nebula. Protostars and Planets IV is also the first book to include chapters describing the discoveries of extrasolar planets, brown dwarfs, and Edgeworth-Kuiper Belt objects, and the first to include high-resolution optical and near-infrared images of protoplanetary disks. Protostars and Planets IV is an unsurpassed reference not only for established researchers but also for younger scientists whose imagination and work will lead to tomorrow's discoveries.
Author: Peter G. Jonker
Publisher: Springer
ISBN: 9789402421453
Category : Science
Languages : en
Pages : 589
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This volume provides an overview of the fast-developing field of tidal disruption events. For several decades, astronomers speculated that a hapless star could wander too close to a massive black hole and be torn apart by tidal forces. Yet it is only with the recent advent of wide-field transient surveys that such events have been detected. Written by a team of prominent researchers, the chapters detail the discoveries made so far in this burgeoning field of study across the entire electromagnetic spectrum, from gamma-rays through X-rays, ultra-violet, optical, infrared, and radio. In addition, they show how tidal disruption events can be used to study the properties of otherwise undetectable supermassive black holes; the populations and dynamics of stars in galactic nuclei; the physics of black hole accretion, including the potential to detect relativistic effects near a SMBH; and the physics of (radio) jet formation and evolution in a pristine environment. Finally, the book outlines important outstanding questions about TDEs. With more than 100 color images, the volume will be useful to researchers and others interested in learning more about this promising area of astrophysics. Previously published in Space Science Reviews in the Topical Collection “The Tidal Disruption of Stars by Massive Black Holes”
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 974
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