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 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 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 Long Time Scale Hard X ray Variability in Seyfert 1 Galaxies written by Alex Gary Markowitz and published by . This book was released on 2003 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Variability of Active Galactic Nuclei written by Hugh Richard Miller and published by . This book was released on 1991 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active galactic nuclei (AGN), the most powerful objects in the universe, continue to receive a great deal of attention from observational astronomers & theorists. This book collects the results presented at a meeting held at Georgia State University in May 1990 on the topic of variability in active galactic nuclei. It is clear that careful analysis of variability over many wave bands is likely to give clues to the nature of the central engine in AGN. The contributions are grouped in themes: multifrequency variability, UV-optical-IR variability, radio variability, & X-ray variability. One of the most exciting results reported here is that many blazars exhibit micro-variability. There is an important group of papers on NGC 5548 & other Seyfert galaxies. The meeting in Atlanta provided the first opportunity for discussion for those who participated in the worldwide campaign to observe NGC 5548, & new results are also announced for many quasars, Seyfert galaxies, BL Lacertae objects, & radio galaxies. The observational data are interspersed with theoretical insights that enable us to better understand the physical conditions & processes in galactic nuclei, including giant black holes thought to lurk in their cores.
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 Radio X ray Variability and Structure Investigation of Seyfert Galaxy NGC 4051 written by Sadie Jones and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is an investigation into the emission from an individual Narrow Line Seyfert 1 (NLS1) Active Galactic Nuclei (AGN) NGC 4051. NLS1s have all the properties of Seyfert galaxies but show peculiar characteristics, including the nar- rowest Balmer lines, strongest Fe 11 emission and extreme properties in the X-rays. NGC 4051, is one of the most X-ray bright Seyferts and it has been studied exten- sively by a number of X-ray observatories. Recent studies have also revealed that Seyfert cores are variable at radio wavelengths, however, there are very few Seyfert radio variability investigations, and this is one of the first that also investigates the radiolX-ray Get/disc) coupling. It has been known for some time that both the X-ray and continuum radio observations provide an optimal tool to access the innermost regions of the AGN. A combination of X-ray, radio and optical data is used here to give an in depth analysis of both the core and extended emission regions of NLS 1 NGC 405l. This work reveals that there is no clear evidence for radio variability in the core emission of NGC 4051 at 8.4 GHz with the possible exception of very low ampli- tude rv 0.12 mJy variations detected in VLA A configuration. Deep VLA obser- vations reveal a mean spectral index value of a rv -0.3 for the core, suggesting a self absorbed jet. The surrounding radio emission has steeper spectral index values in the range of -0.5 a
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 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 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 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 Fourier Analysis of Seyfert Galaxy X ray Variability written by Jennifer L. Sokoloski and published by . This book was released on 1989 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Lectures on the Starburst AGN Connection written by D. Kunth and published by World Scientific. This book was released on 2001 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: A group of leading experts in the field of starbursts and active galactic nuclei have joined hands to produce this review volume which covers the starburst-AGN connection, and the tests to be carried out with the upcoming new astronomical facilities to ascertain the relevance of both components to the formation and evolution of galaxies.The book is addressed to advanced graduate students and researchers in the fields of active galactic nuclei and young galaxies.
Download or read book Variability of Galactic and Extragalactic X ray Sources written by Aldo Treves and published by . This book was released on 1987 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
