Download or read book An Investigation Into the Broad Emission Lines in Active Galactic Nuclei written by Karoline M. Gilbert and published by . This book was released on 2002 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Introduction to Active Galactic Nuclei written by Bradley M. Peterson and published by Cambridge University Press. This book was released on 1997-02-13 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: How can we test if a supermassive black hole lies at the heart of every active galactic nucleus? What are LINERS, BL Lacs, N galaxies, broad-line radio galaxies and radio-quiet quasars and how do they compare? This timely textbook answers these questions in a clear, comprehensive and self-contained introduction to active galactic nuclei - for graduate students in astronomy and physics. The study of AGN is one of the most dynamic areas of contemporary astronomy, involving one fifth of all research astronomers. This textbook provides a systematic review of the observed properties of AGN across the entire electromagnetic spectrum, examines the underlying physics, and shows how the brightest AGN, quasars, can be used to probe the farthest reaches of the Universe. This book serves as both an entry point to the research literature and as a valuable reference for researchers in the field.
Download or read book The Physics and Evolution of Active Galactic Nuclei written by Hagai Netzer and published by Cambridge University Press. This book was released on 2013-09-16 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive introduction to the theory underpinning our study of active galactic nuclei and the ways we observe them.
Download or read book Physics of Active Galactic Nuclei at all Scales written by Danielle Alloin and published by Springer. This book was released on 2006-09-07 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a collection of lecture notes written by recognized experts in the field of Active Galactic Nuclei (AGN). The collection is aimed at providing both an introduction and at the same time an overview of the state-of-the-art of AGN research. This book also addresses the still not entirely understood link of an AGN with its host galaxy and also the related question of the birth and growth of massive black holes in the Universe.
Download or read book Emission Lines in Active Galactic Nuclei written by Rutherford Appleton Laboratory. Workshop on Astronomy and Astrophysics and published by . This book was released on 1987 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: The spectra of active galactic nuclei and quasars are characterised by permitted broad emission lines of very different ionization levels. Only a small fraction of the total luminosity of an active galactic nucleus or a quasar is emitted in these lines and yet a very generous amount of telescope time is spent observing these lines and an equally generous amount of computer time is spent modelling them. Why ....................? Because; "Sometimes you can't stick your head in the engine so you have to examine the exhaust."--D E Osterbrock. There cannot be a better rational than this for investigating line emission in active galaxies. The seventh RAL Workshop on Astronomy and Astrophysics was organised to "assess the damage" and to explore new ideas for understanding line emission in active galaxies. No particular line of approach was defined for new models, before a "revised standard model" can be accepted the following questions (posed by the participants in the workshop) will have to be answered.
Download or read book X ray Studies of the Central Engine in Active Galactic Nuclei with Suzaku written by Hirofumi Noda and published by Springer. This book was released on 2015-12-07 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this research was to use the X-ray satellite Suzaku to establish a picture of a central engine that effectively converts the gravitational energy of accreting matter onto the supermassive black hole to a huge amount of radiation in an active galactic nucleus. Although the engine is known to consist of a Comptonizing corona and an accretion disk, its image has remained unclear because primary emissions, coming directly from the engine, cannot be identified in X-ray spectra without models. The book describes a technique of time variability assisted spectral decomposition to model-independently examine X-ray signals, and how this was applied to the Suzaku archive data of active galactic nuclei. As a result, at least three distinct primary X-ray components have been discovered in an X-ray from an active galactic nucleus, presumably indicating a novel picture that the engine is composed of multiple coronae with different physical properties in an accretion flow. Furthermore, the determination of the spectral shapes of the primary X-rays has a significant impact on estimations of black hole spins, because it is essential to quantify reprocessed X-ray spectra. The successful model-independent decomposition of X-ray spectral components with flux variations of active galactic nuclei is likely to be effective in future data analyses from the soon-to-be-launched Japanese X-ray satellite ASTRO-H, which is capable of achieving unprecedented fine spectros copy and broad energy band coverage.
Download or read book Active Galactic Nuclei Mergers and Outflows written by Robert Scott Barrows and published by . This book was released on 2013 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: I have investigated the nature of a subset of active galactic nuclei (AGN) which show double peaks in their characteristic optical and ultraviolet emission lines. I have performed this investigation through studies of the broad emission line regions (BLRs), which are produced less than 1 pc from the central supermassive black hole (SMBH), and the narrow emission line regions (NLRs), which originate at larger (kpc) distances. The BLR studies consist of detailed line modeling of two individual quasars with double-peaked broad emission line profiles. The modeling suggests there are two primary interpretations of the complex broad line profiles. The first possiblity is line emission from the surface of an asymmetric and/or non-uniform accretion disk of a low-accretion rate AGN; these sources are known as double-peaked emitters and account for only about 3% of the quasar population. The second possibility is line emission from the BLRs of two actively accreting SMBHs in a close (
Download or read book Active Galactic Nuclei written by Julian H. Krolik and published by Princeton University Press. This book was released on 2021-03-09 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first comprehensive treatment of active galactic nuclei--the cosmic powerhouses at the core of many distant galaxies. The term active galactic nuclei refers to quasars, radio galaxies, Seyfert galaxies, blazars, and related objects, all of which are believed to share a similar central engine--a supermassive black hole many times the mass of the Sun. Astrophysicists have studied these phenomena for the past several decades and have begun to develop a consensus about many of their properties and internal mechanisms. Julian Krolik, one of the world's leading authorities on the subject, sums up leading ideas from across the entire range of research, making this book an invaluable resource for astronomers, physicists interested in applications of the theory of gravitation, and graduate students. Krolik begins by addressing basic questions about active galactic nuclei: What are they? How can they be found? How do they evolve? He assesses the evidence for massive black holes and considers how they generate power by accretion. He discusses X-ray and g-ray emission, radio emission and jets, emission and absorption lines, anisotropic appearance, and the relationship between an active nucleus and its host galaxy. He explores the mysteries of what ignites, fuels, and extinguishes active galactic nuclei, and concludes with a general review of where the field now stands. The book is unique in paying careful attention to relevant physics as well as astronomy, reflecting in part the importance of general relativity to understanding active galactic nuclei. Clear, authoritative, and detailed, this is crucial reading for anyone interested in one of the most dynamic areas of astrophysics today.
Download or read book Observational Constraints on the Influence of Active Galactic Nuclei on the Evolution of Galaxies written by Christopher Mark Harrison and published by Springer. This book was released on 2016-01-20 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This prize-winning Ph.D. thesis by Chris Harrison adopts a multi-faceted approach to address the lack of decisive observational evidence, utilising large observational data sets from several world-leading telescopes. Developing several novel observational techniques, Harrison demonstrated that energetic winds driven by Active Galactic Nuclei (AGN) are found in a large number of galaxies, with properties in agreement with model predictions. One of the key unsolved problems in astrophysics is understanding the influence of AGN, the sites of growing supermassive black holes, on the evolution of galaxies. Leading theoretical models predict that AGN drive energetic winds into galaxies, regulating the formation of stars. However, until now, we have lacked the decisive observational evidence to confirm or refute these key predictions. Careful selection of targets allowed Harrison, to reliably place these detailed observations into the context of the overall galaxy population. However, in disagreement with the model predictions, Harrison showed that AGN have little global effect on star formation in galaxies. Theoretical models are now left with the challenge of explaining these results.
Download or read book Active Galactic Nuclei written by Ian Robson and published by Wiley-Blackwell. This book was released on 1996 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the energy source and physical processes within active galaxies are the most challenging areas of current research. Using a logical format and easy-to-follow explanations, Robson demonstrates the crucial connections between observation and theory, illustrating how diverse classes of active galaxies fit into the contemporary perspective. Summary sections explain the physical concepts behind the mathematics.
Download or read book Emission line Properties of Active Galactic Nuclei and an Experiment in Integrated Guided inquiry Science Classes and Implications for Teaching Astronomy written by Randi Renae Ludwig and published by . This book was released on 2012 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation examines two broad topics -- emission line properties of active galactic nuclei (AGN) and the effect of hands-on, integrated science courses on student understanding of astronomy. To investigate trends in overall properties of emission lines in AGN, we apply principal component analysis (PCA) to the fluxes in the H [beta] - (O III) region of a sample of 9046 spectroscopically-identified broad-line AGN from the Sloan Digital Sky Survey (SDSS) Data Release 5 with a redshift range of 0.1
Download or read book Steps Toward Determination of the Size and Structure of the Broad Line Region in Active Galactic Nuclei 8 An Intensive Hst Iue and Ground Based St written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-11-14 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the data and initial results from a combined HST/IUE/ground-based spectroscopic monitoring campaign on the Seyfert 1 galaxy NGC 5548 that was undertaken in order to address questions that require both higher temporal resolution and higher signal-to-noise ratios than were obtained in our previous multiwavelength monitoring of this galaxy in 1988-89. IUE spectra were obtained once every two days for a period of 74 days beginning on 14 March 1993. During the last 39 days of this campaign, spectroscopic observations were also made with the HST Faint Object Spectrograph (FOS) on a daily basis. Ground-based observations, consisting of 165 optical spectra and 77 photometric observations (both CCD imaging and aperture photometry), are reported for the period 1992 October to 1993 September, although much of the data are concentrated around the time of the satellite-based program. These data constitute a fifth year of intensive optical monitoring of this galaxy. In this contribution, we describe the acquisition and reduction of all of the satellite and ground-based data obtained in this program. We describe in detail various photometric problems with the FOS and explain how we identified and corrected for various anomalies. During the HST portion of the monitoring campaign, the 1350 A continuum flux is found to have varied by nearly a factor of two. In other wavebands, the continuum shows nearly identical behavior, except that the amplitude of variability is larger at shorter wavelengths, and the continuum light curves appear to show more short time-scale variability at shorter wavelengths. The broad emission lines also vary in flux, with amplitudes that are slightly smaller than the UV continuum variations and with a small time delay relative to the UV continuum. On the basis of simple time-series analysis of the UV and optical continuum and emission line light curves, we find (1) that the ultraviolet and optical continuum variations are virtually simultaneous, wi...
Download or read book Physics of Active Galactic Nuclei at all Scales written by Danielle Alloin and published by Springer. This book was released on 2009-09-02 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a collection of lecture notes written by recognized experts in the field of Active Galactic Nuclei (AGN). The collection is aimed at providing both an introduction and at the same time an overview of the state-of-the-art of AGN research. This book also addresses the still not entirely understood link of an AGN with its host galaxy and also the related question of the birth and growth of massive black holes in the Universe.
Download or read book Reverberation Mapping of the Broad line Region in Active Galactic Nuclei written by Rutherford Appleton Laboratory. Workshop on Astronomy and Astrophysics and published by . This book was released on 1994 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Central Activity in Galaxies written by Aage Sandqvist and published by Springer. This book was released on 1993-01-22 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: This outstanding collection of surveys addresses graduate and predoctoral students. It reports on theoretical research and observational data on active galactic nuclei: The enigma of the nuclei of galaxies with their central "monster" driving the vast range of activity observed in quasars, radio galaxies, Seyferts, starburst galaxies and even our own Galaxy are explored in this volume. Topics covered include: the impact of recent measurements in the infrared and radio region on our knowledge of thenucleus of our Galaxy; the spectra and classification of active galactic nuclei, the properties of their host galaxies, their cosmological distribution and evolution, the role of stars and thehydrodynamics of the interstellar medium in the nuclei; the description of the inner parsec of a standard active galactic nucleus based on direct interpretation of the observations; the infrared activity of galaxies; the physics of radio galaxies and their jets, emphasizing the physics ofgas flow and high-energy particle interactions as well as shock acceleration. These are all discussed in considerable depth and presented inself-contained chapters with exhaustive reference lists of the scientific literature.
Download or read book Quasars at All Cosmic Epochs written by Paola Marziani and published by Frontiers Media SA. This book was released on 2018-10-05 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Astrophysics Of Gas Nebulae and Active Galactic Nuclei written by Donald E. Osterbrock and published by University Science Books. This book was released on 2006 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thoroughly revised and expanded throughout, the new edition is a graduate-level text and reference book on gaseous nebulae, nova and supernova remnants. Much of the new data and new images are from the Hubble Space Telescope with two wholly new chapters being added along with other new features. The previous edition which was tried and tested for thirty years has now been succeeded by a revised, updated, larger edition, which will be valuable to anyone seriously interested in astrophysics.
