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This thesis describes the application of a Monte Carlo radiative transfer code to accretion disc winds in two types of systems spanning 9 orders of magnitude in mass and size. In both cases, the results provide important new insights. On small scales, the presence of disc winds in accreting white dwarf binary systems has long been inferred from the presence of ultraviolet absorption lines. Here, the thesis shows that the same winds can also produce optical emission lines and a recombination continuum. On large scales, the thesis constructs a simple model of disc winds in quasars that is capable of explaining both the observed absorption and emission signatures – a crucial advance that supports a disc-wind based unification scenario for quasars. Lastly, the thesis also includes a theoretical investigation into the equivalent width distribution of the emission lines in quasars, which reveals a major challenge to all unification scenarios.
Theory of Accretion Disks by F. Meyer,Wolfgang J. Duschl,Juhan Frank,Emmi Meyer-Hofmeister Pdf
With the advent of space observatories and modern developments in ground based astronomy and concurrent progress in the theoretical understanding of these observations it has become clear that accretion of material on to compact objects is an ubiquitous mechanism powering very diverse astrophysical sources ranging in size and luminosity by many orders of magnitude. A problem common to these systems is that the material accreted must in general get rid of its angular momentum and this leads to the formation of an Accretion Disk which allows angular momentum re-distribution and converts potential energy into radiation with an efficiency which can be higher than the nuclear burning yield. These systems range in size from quasars and active galactic nuclei to accretion disks around forming stars and the early solar system and to compact binaries such as cataclysmic variables and low-mass X-ray binaries. Other objects that should be mentioned in this context are 88433, the black hole binary candidates, and possibly gamma-ray burst sources. Observations of these systems have provided important constraints for theoretical accretion disk models on widely differing scales, lumi nosities, mass-transfer rates and physical environments.
Author : Thomas J. Maccarone,Robert P. Fender,Luis C. Ho Publisher : Springer Science & Business Media Page : 276 pages File Size : 49,5 Mb Release : 2007-01-28 Category : Science ISBN : 9781402040856
From X-ray Binaries to Quasars: Black Holes on All Mass Scales by Thomas J. Maccarone,Robert P. Fender,Luis C. Ho Pdf
This volume brings together contributions from many of the world's leading authorities on black hole accretion. The papers within represent part of a new movement to make use of the relative advantages of studying stellar mass and supermassive black holes, and to bring together the knowledge gained from the two approaches. The topics discussed include black hole observational and theoretical work-variability, spectroscopy, disk-jet connections, and multi-wavelength campaigns on black holes.
Quasars at All Cosmic Epochs by Paola Marziani,Mauro D'Onofrio,Ascensión del Olmo,Deborah Dultzin Pdf
The last 50 years have seen a tremendous progress in the research on quasars. From a time when quasars were unforeseen oddities, we have come to a view that considers quasars as active galactic nuclei, with nuclear activity a coming-of-age experienced by most or all galaxies in their evolution. We have passed from a few tens of known quasars of the early 1970s to the 500,000 listed in the catalogue of the Data Release 14 of the Sloan Digital Sky Survey. Not surprisingly, accretion processes on the central black holes in the nuclei of galaxies — the key concept in our understanding of quasars and active nuclei in general — have gained an outstanding status in present-day astrophysics. Accretion produces a rich spectrum of phenomena in all bands of the electromagnetic spectrum. The power output of highly-accreting quasars has impressive effects on their host galaxies. All the improvement in telescope light gathering and in computing power notwithstanding, we still miss a clear connection between observational properties and theory for quasars, as provided, for example, by the H-R diagram for stars. We do not yet have a complete self-consistent view of nuclear activity with predictive power, as we do for main-sequence stellar sources. At the same time quasars offer many “windows open onto the unknown". On small scales, quasar properties depend on phenomena very close to the black hole event horizon. On large scales, quasars may effect evolution of host galaxies and their circum-galactic environments. Quasars’ potential to map the matter density of the Universe and help reconstruct the Universe’s spacetime geometry is still largely unexploited. The times are ripe for a critical assessment of our present knowledge of quasars as accreting black holes and of their evolution across the cosmic time. The foremost aim of this research topic is to review and contextualize the main observational scenarios following an empirical approach, to present and discuss the accretion scenario, and then to analyze how a closer connection between theory and observation can be achieved, identifying those aspects of our understanding that are still on a shaky terrain and are therefore uncertain knowledge. This research topic covers topics ranging from the nearest environment of the black hole, to the environment of the host galaxies of active nuclei, and to the quasars as markers of the large scale structure and of the geometry of spacetime of the Universe. The spatial domains encompass the accretion disk, the emission and absorption regions, circum-nuclear starbursts, the host galaxy and its interaction with other galaxies. Systematic attention is devoted to some key problems that remain outstanding and are clearly not yet solved: the existence of two quasar classes, radio quiet and radio loud, and in general, the systematic contextualization of quasar properties the properties of the central black hole, the dynamics of the accretion flow in the inner parsecs and the origin of the accretion matter, the quasars’ small and large scale environment, the feedback processes produced by the black hole into the host galaxy, quasar evolutionary patterns from seed black holes to the present-day Universe, and the use of quasars as cosmological standard candles. The timing is appropriate as we are now witnessing a growing body of results from major surveys in the optical, UV X, near and far IR, and radio spectral domains. Radio instrumentation has been upgraded to linear detector — a change that resembles the introduction of CCDs for optical astronomy — making it possible to study radio-quiet quasars at radio frequencies. Herschel and ALMA are especially suited to study the circum-nuclear star formation processes. The new generation of 3D magnetohydrodynamical models offers the prospective of a full physical modeling of the whole quasar emitting regions. At the same time, on the forefront of optical astronomy, applications of adaptive optics to long-slit spectroscopy is yielding unprecedented results on high redshift quasars. Other measurement techniques like 2D and photometric reverberation mapping are also yielding an unprecedented amount of data thanks to dedicated experiments and instruments. Thanks to the instrumental advances, ever growing computing power as well as the coming of age of statistical and analysis techniques, the smallest spatial scales are being probed at unprecedented resolution for wide samples of quasars. On large scales, feedback processes are going out of the realm of single-object studies and are entering into the domain of issues involving efficiency and prevalence over a broad range of cosmic epochs. The Research Topic "Quasars at all Cosmic Epochs" collects a large fraction of the contributions presented at a meeting held in Padova, sponsored jointly by the National Institute for Astrophysics, the Padova Astronomical Observatory, the Department of Physics and Astronomy of the University of Padova, and the Instito de Astrofísica de Andalucía (IAA) of the Consejo Superiór de Investigación Cientifica (CSIC). The meeting has been part of the events meant to celebrate the 250th anniversary of the foundation of the Padova Observatory.
Fifty Years of Quasars by Mauro D'Onofrio,Paola Marziani,Jack W. Sulentic Pdf
The 50th anniversary of the discovery of quasars in 1963 presents an interesting opportunity to ask questions about the current state of quasar research. Formatted as a series of interviews with noted researchers in the field, each of them asked to address a specific set of questions covering topics selected by the editors, this book deals with the historical development of quasar research and discusses how advances in instrumentation and computational capabilities have benefitted quasar astronomy and have changed our basic understanding of quasars. In the last part of the book the interviews address the current topic of the role of quasars in galaxy evolution. They summarise open issues in understanding active galactic nuclei and quasars and present an outlook regarding what future observational facilities both on the ground and in space might reveal. Its interview format, the fascinating topic of quasars and black holes, and the lively recollections and at times controversial views of the contributors make this book both rewarding and a pleasure to read!
Accretion Disks in Compact Stellar Systems by J. Craig Wheeler Pdf
Accretion disks in compact stellar systems containing white dwarfs, neutron stars or black holes are the principal laboratory for understanding the role of accretion disks in a wide variety of environments from proto-stars to quasars. Recent work on disk instabilities and dynamics has given a new theoretical framework with which to study accretion disks. Modeling of time-dependent phenomena provides new insight into the causes and interpretation of photometric and spectroscopic variability and new constraints on the fundamental physical problem -- the origin of viscosity in accretion disks. This book contains expert reviews on the nature of limit cycle thermal instabilities and a variety of closely related topics from the theory of angular momentum transport to eclipse mapping of the disk structure. The result is a comprehensive contemporary survey of the structure and evolution of accretion disks in compact binary systems.
A current account of quasar astronomy that not only summarizes existing results from various techniques but refers to the potentialities of new instruments. All aspects of quasar spectroscopy are discussed and techniques for analyzing quasar data are summarized.
Galactic and Extragalactic Star Formation by Ralph E. Pudritz,Michel Fich Pdf
Recent advances in the instrumentation used to observe star forming regions in both our own Milky Way and in external galaxies have transformed the subject from a phenomenological pursuit into an increasingly unified, physical science. High resolution centimetre, millimetre, infrared, and optical studies of local star forming clouds have allowed us to probe the physics of star formation down to spatial scales approaching those of the solar system. These developments make it possible to better constrain the basic physical processes underlying star formation itself. At the same time, these new instruments have placed extragalactic studies on a footing detailed enough to allow comparison with star forming regions within our own galaxy. This revolution means that we will soon be able to link the physics of local star forming regions to the global star forming properties of galaxies. The entire structure of this NATO Advanced Study Institute was designed to explore this new view of the subject. This Institute on "Galactic and Extragalactic Star Formation" was held from June 21 -July 4, 1987 at the Conference Centre in the village of Whistler, British Columbia, Canada. The informal atmosphere of this lovely mountain resort stim ulated many valuable scientific exchanges. The Institute was funded by a major grant from NATO Scientific Affairs. Additional financial and I.I1oral assistance was provided by the Canadian Institute for Theoretical Astrophysics (CITA) and Mc Master University.
Theory of Accretion Disks by F. Meyer,Wolfgang J. Duschl,Juhan Frank,Emmi Meyer-Hofmeister Pdf
With the advent of space observatories and modern developments in ground based astronomy and concurrent progress in the theoretical understanding of these observations it has become clear that accretion of material on to compact objects is an ubiquitous mechanism powering very diverse astrophysical sources ranging in size and luminosity by many orders of magnitude. A problem common to these systems is that the material accreted must in general get rid of its angular momentum and this leads to the formation of an Accretion Disk which allows angular momentum re-distribution and converts potential energy into radiation with an efficiency which can be higher than the nuclear burning yield. These systems range in size from quasars and active galactic nuclei to accretion disks around forming stars and the early solar system and to compact binaries such as cataclysmic variables and low-mass X-ray binaries. Other objects that should be mentioned in this context are 88433, the black hole binary candidates, and possibly gamma-ray burst sources. Observations of these systems have provided important constraints for theoretical accretion disk models on widely differing scales, lumi nosities, mass-transfer rates and physical environments.
GravItational Lensing of Quasars by Alexander Eigenbrod Pdf
The universe, in all its richness, diversity and complexity, is populated by a myriad of intriguing celestial objects. Among the most exotic of them are gravitationally lensed quasars. A quasar is an extremely bright nucleus of a galaxy, and when such an object is gravitationally lensed, multiple images of the quasar are produced - this phenomenon
