Download or read book X ray Spectral Variability of Seyfert Galaxies written by Andrew Lobban 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 Fast Spectral Variability in the X ray Emission of Accreting Black Holes written by Chris Skipper and published by Springer. This book was released on 2014-09-04 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis brings together the various techniques of X-ray spectral analysis in order to examine the properties of black holes that vary in mass by several orders of magnitude. In all these systems it is widely accepted that the X-ray emission is produced by Compton up-scattering of lower energy seed photons in a hot corona or accretion flow, and here these processes are examined through a study of the X-ray spectral variability of each source. A new technique is introduced, in which models are fitted to over 2 million X-ray spectra on time-scales as short as 16 ms, and subsequently it is shown that the nature of the correlation between intensity and spectral index is strongly dependent upon the spectral state of the black hole. Finally, the results of an extensive survey of nearby galactic nuclei using the Chandra X-ray telescope are presented in the form of images and spectra, and these results are used along with data from the literature to search for Compton-thick nuclei.
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 The X ray Variability of Seyfert Galaxies written by Kevin Marshall and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Strong and variable X-ray emission has long been known to be a universal property of active galaxies. However, despite years of study, the exact nature of the variability remains relatively unknown. We present here results of a multi-year monitoring campaign of a sample of Seyfert galaxies (3C 120, Mkn 509, 3C 390.3, and Akn 120), carried out using the Rossi X-ray Timing Explorer (RXTE). For Mkn 509, we also present results of optical monitoring. Mkn 509 shows a strong correlation between X-ray and optical variations, with the optical leading the X-ray by 25 days. We also investigate the rms-flux relationship in our sample. The two radio loud objects in our sample (3C 120, 3C 390.3) show a clear correlation between flux and rms variability, while the two radio quiet objects (Mkn 509, Akn 120) show no such relationship. Monte Carlo simulations were used to estimate the shape of the underlying power spectrum, and we find that all of our objects have a break frequency below which the power spectrum flattens. The relationship between optical and X-ray variability is discussed, with lags occurring most likely as a result of instabilities or changes in accretion flow propagating inwards through the disk. We also discuss possible physical timescales that could be related to the break frequency, along with connections to galactic X-ray binaries.
Download or read book The Complex Broad band X ray Spectra of Seyfert Galaxies written by Kimberly Weaver and published by . This book was released on 1993 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Variability of Blazars written by E. VALTAOJA (Ed) and published by Cambridge University Press. This book was released on 1992 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: Blazars (also known as BL Lac objects), first discovered in 1978, are unusually energetic objects in the extragalactic universe. About 200 are known or suspected. They are radio sources with highly variable optical and radio emission, as well as high polarisation, and their optical spectra normally have no distinguishable features. It is generally accepted that they belong to that class of galaxies with active galactic nuclei, which are presumed to be driven by infall of matter to a supermassive black hole. In this book researchers give a complete summary of the observations of blazars and the theoretical interpretation. A comprehensive listing of confirmed and candidate objects is included. Mechanisms in which the variability can arise from shocks and relativistic jets are discussed. There are at least four different answers given to the question: what is a blazar? This book is a complete overview of the violent activity observed in these extreme active galactic nuclei.
Download or read book The X ray Background written by Xavier Barcons and published by Cambridge University Press. This book was released on 1992-07-31 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of the current observational knowledge and understanding of the cosmic X-ray background.
Download or read book Compact Stellar X ray Sources written by Walter Lewin and published by Cambridge University Press. This book was released on 2006-04-06 with total page 667 pages. Available in PDF, EPUB and Kindle. Book excerpt: X-ray astronomy is the prime available window on astrophysical compact objects: black holes, neutron stars and white dwarfs. In this book, prominent experts provide a comprehensive overview of the observations and astrophysics of these objects. This is a valuable reference for graduate students and active researchers.
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 The Relationship Between the X ray and Optical Variability in Seyfert Galaxies written by Elmé Breedt Lategan and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book From X ray Binaries to Quasars Black Holes on All Mass Scales written by Thomas J. Maccarone and published by Springer Science & Business Media. This book was released on 2007-01-28 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Science With The Cherenkov Telescope Array written by The Cta Consortium and published by World Scientific. This book was released on 2018-12-31 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the science to be carried out by the upcoming Cherenkov Telescope Array, a major ground-based gamma-ray observatory that will be constructed over the next six to eight years. The major scientific themes, as well as core program of key science projects, have been developed by the CTA Consortium, a collaboration of scientists from many institutions worldwide.CTA will be the major facility in high-energy and very high-energy photon astronomy over the next decade and beyond. CTA will have capabilities well beyond past and present observatories. Thus, CTA's science program is expected to be rich and broad and will complement other major multiwavelength and multimessenger facilities. This book is intended to be the primary resource for the science case for CTA and it thus will be of great interest to the broader physics and astronomy communities. The electronic version (e-book) is available in open access.
Download or read book Frontiers of X Ray Astronomy written by A. C. Fabian and published by Cambridge University Press. This book was released on 2004-07-08 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: X-ray astronomy has undergone a revolution in recent years. With the launch of two orbiting observatories, Chandra and XMM-Newton, astronomers are now able to obtain spectra and images at a higher resolution than ever before. Observations have had a major impact on topics ranging from protostars to cosmology. The contributions in this 2004 work, by leading authorities in the field, originate from a Royal Society Discussion Meeting that was held to review results from the current generation of X-ray telescopes, and set them in context. This book is a valuable reference for research astronomers and graduate students wishing to understand the latest developments in this exciting field.
Download or read book The Relationship Between the X ray and Optical Variability in Seyfert Galaxies written by Elme Breddt Lategan and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Interplay Among Black Holes Stars and ISM in Galactic Nuclei IAU S222 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2004 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: How massive are the largest and smallest nuclear black holes in galaxies? Why are the masses of nuclear black holes proportional to those of their host galaxy bulges? How is nuclear activity triggered? What are the observational signatures of such processes? What are the connections between the active nucleus, stars and interstellar medium in galaxies? Answers to these questions are addressed in this book, which presents a compilation of 191 works covering recent observations from X-rays to radio wavelengths, as well as theoretical modeling of accretion disks, stellar populations and galaxy and black hole evolution. This volume presents the nuclear activity as a phase in the life of a galaxy, which is intimately connected to the evolution of its stars and interstellar medium. It brings together recent developments in topics covering most aspects of galaxy evolution, and is a valuable resource for astronomers and graduate students working in extragalactic astronomy.
Download or read book Variability of Active Galaxies written by Wolfgang J. Duschl and published by Springer. This book was released on 1991 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: The enormous amounts of energy radiated from the active nuclei of galaxies vary on short time scales, and the emission regions are difficult to observe. To provide a complete understanding of these phenomena a wide variety of studies is presented in this volume. The contributions are broadly divided between line and continuum variability, with observational results, methodological approaches, and theoretical models accompanying each. The final part is devoted to the important aspect of propagation-induced variability.
Download or read book Ionized Absorbers in Active Galactic Nuclei and Very Steap Soft X Ray Quasars written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Steep soft X-ray (0.1-2 keV) quasars share several unusual properties: narrow Balmer lines, strong Fe II emission, large and fast X-ray variability, and a rather steep 2-10 keV spectrum. These intriguing objects have been suggested to be the analogues of Galactic black hole candidates in the high, soft state. We present here results from ASCA observations for two of these quasars: NAB 0205 + 024 and PG 1244 + 026. Both objects show similar variations (factor of approximately 2 in 10 ks), despite a factor of approximately 10 difference in the 0.5-10 keV luminosity (7.3 x 10(exp 43) erg/s for PG 1244 + 026 and 6.4 x 10(exp 44) erg/s for NAB 0205 + 024, assuming isotropic emission, H(sub 0) = 50.0 and q(sub 0) = 0.0). The X-ray continuum of the two quasars flattens by 0.5-1 going from the 0.1-2 keV band towards higher energies, strengthening recent results on another half-dozen steep soft X-ray active galactic nuclei. PG 1244 + 026 shows a significant feature in the '1-keV' region, which can be described either as a broad emission line centered at 0.95 keV (quasar frame) or as edge or line absorption at 1.17 (1.22) keV. The line emission could be a result of reflection from a highly ionized accretion disc, in line with the view that steep soft X-ray quasars are emitting close to the Eddington luminosity. Photoelectric edge absorption or resonant line absorption could be produced by gas outflowing at a large velocity (0.3-0.6 c).Fiore, Fabrizio and White, Nicholas (Technical Monitor)Goddard Space Flight CenterX RAY ASTRONOMY; X RAY SOURCES; SEYFERT GALAXIES; ACTIVE GALACTIC NUCLEI; QUASARS; BLACK HOLES (ASTRONOMY); BALMER SERIES; EMISSION SPECTRA; LINE SPECTRA; SPECTRUM ANALYSIS; VARIABILITY; DATA REDUCTION
