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High Frequency Very Long Baseline Interferometry Obeservations Of Active Galactic Nuclei
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Book Synopsis High Frequency Very Long Baseline Interferometry Obeservations of Active Galactic Nuclei by : Geoffrey Copeland Bower
Download or read book High Frequency Very Long Baseline Interferometry Obeservations of Active Galactic Nuclei written by Geoffrey Copeland Bower and published by . This book was released on 1997 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ARISE written by and published by . This book was released on 1999 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Multi-frequency Time Variability of Active Galactic Nuclei by : Ritaban Chatterjee
Download or read book Multi-frequency Time Variability of Active Galactic Nuclei written by Ritaban Chatterjee and published by . This book was released on 2010 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In an active galactic nucleus (AGN), the central region of a galaxy is brighter than the rest of the galaxy and sometimes -10,000 times as bright as an average galaxy. The extremely high luminosities of AGNs are thought to be produced by the accretion of matter onto a supermassive black hole (1 million-10 billion solar masses). In many cases AGNs produce two oppositely directed jets of magnetized plasma moving at near-light speed that are luminous over a large range of wavelengths. Understanding the structure and ongoing physical processes of AGNs has important implications in cosmology, galaxy formation theory, black hole physics and other areas of astronomical interest. Due to their large distances, AGNs are not spatially resolved with current and near-future technologies except by radio interferometry. However, we can use time variability, one of the defining properties of AGNs, to probe the location and physical processes related to the emission at resolutions even finer than provided by very long baseline interferometry (VLBI). This dissertation employs extensive multi-frequency monitoring data of the blazar 3C 279 (over >10 years) and the radio galaxies 3C 120 and 3C 111 (>5 years) at X-ray, optical, and radio wavebands, as well as monthly VLBI images. The study develops and applies a set of statistical tools to characterize the time variability of AGNs, including power spectral density (PSD), discrete cross-correlation functions and calculation of their significance. This involves generation of light curves simulated randomly from the previously calculated PSDs. Numerical models of the time variable emission spectrum of the jets and accretion disk-corona system relate the variability to the physics and locations of the various emission regions of the AGN. The analysis leads to the inferences that (1) multiple nonthermal emission zones occur in the jet, (2) acceleration of the highest energy electrons in the jet is often gradual, (3) optical emission from the radio galaxies arises mainly in the accretion disk, and (4) the X-ray emitting hot electrons above the disk lie within about 50 gravitational radii from the black hole.
Book Synopsis Are There Rotation Measure Gradients Across Active Galactic Nuclei Jets? by : Gregory Benjamin Taylor
Download or read book Are There Rotation Measure Gradients Across Active Galactic Nuclei Jets? written by Gregory Benjamin Taylor and published by . This book was released on 2010 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on multi-frequency polarimetry very long baseline interferometry observations of active galactic nuclei using the Very Long Baseline Array. These observations are used to construct images of the Faraday rotation measure (RM) in J1613+342, Mrk 501, 3C 371, and BL Lac. Despite having resolved the jets in total intensity and polarization for three of these sources no RM gradients are found. This is in contrast to the large fraction of sources with RM gradients now claimed in the literature and invoked as evidence in support of helical magnetic fields. We propose objective criteria for establishing what constitutes an RM gradient. Furthermore, although we note the absence of simple, monotonic gradients, comparison with simulations could reveal systematic changes in the RM that may be masked by a varying jet orientation.
Book Synopsis Very Long Baseline Interferometry and the VLBA by : J. Anton Zensus
Download or read book Very Long Baseline Interferometry and the VLBA written by J. Anton Zensus and published by . This book was released on 1995 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Open Skies by : Kenneth I. Kellermann
Download or read book Open Skies written by Kenneth I. Kellermann and published by Springer Nature. This book was released on 2020-01-01 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book on the history of the National Radio Astronomy Observatory covers the scientific discoveries and technical innovations of late 20th century radio astronomy with particular attention to the people and institutions involved. The authors have made extensive use of the NRAO Archives, which contain an unparalleled collection of documents pertaining to the history of radio astronomy, including the institutional records of NRAO as well as the personal papers of many of the pioneers of U.S. radio astronomy. Technical details and extensive citations to original sources are given in notes for the more technical readers, but are not required for an understanding of the body of the book. This book is intended for an audience ranging from interested lay readers to professional researchers studying the scientific, technical, political, and cultural development of a new science, and how it changed the course of 20th century astronomy.
Book Synopsis Study of the Variability of Active Galactic Nuclei at Very High Energy with H.E.S.S. by : Gabriel Emery
Download or read book Study of the Variability of Active Galactic Nuclei at Very High Energy with H.E.S.S. written by Gabriel Emery and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Along with the improvement of our knowledge of the Universe, increasingly detailed, varied and precise data sets appeared necessary to solve the remaining unknowns. Experiments thus improved their sensitivities and resolutions but also combined their observations into large multi-messenger and multi-wavelength data sets. If a source is variable the available temporal information can also be used to constrain the possible processes taking place in this source. Blazars are active galactic nuclei displaying important variability with electromagnetic emissions covering a large fraction of the observed electromagnetic spectrum, emitted in a relativistic jet of particles. The H.E.S.S. experiment is an array of Cherenkov telescopes located in Namibia performing astronomical observations using very high energy photons. In this manuscript, reviews of blazar physics, very high energy astronomy and the H.E.S.S. experiment are followed by various worked performed to analyse and use variable data from blazars. Tools were developed in the H.E.S.S. analysis software aiming at improving the analysis of flaring events. Sets of data obtained during flaring events of two blazars (3C 279 and PKS 2022-077) were analysed and put into context with contemporaneous multi-wavelength observations. A new task aiming at characterising blazar flare in a semi-systematic way is also introduced. The manuscript then ends with the results of the exploration of the parameter space of a lepto-hadronic emission model applied to a flare of TXS 0506+056 coincident with the detection of an astrophysical neutrino with IceCube.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992-06 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Interferometry and Synthesis in Radio Astronomy by : A. Richard Thompson
Download or read book Interferometry and Synthesis in Radio Astronomy written by A. Richard Thompson and published by Wiley-Interscience. This book was released on 1986-04-28 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unified description of the theory and practice of radio interferometry and synthesis mapping techniques as they apply to astronomy and geology. Beginning with an historical review, it goes on to provide a detailed description of all aspects of radio inferometry, from basic principles through instrumental design to data reduction. Over 450 original papers and monographs are cited.
Book Synopsis Physics of Active Galactic Nuclei by : Wolfgang J. Duschl
Download or read book Physics of Active Galactic Nuclei written by Wolfgang J. Duschl and published by Springer. This book was released on 1992 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Highlights of Spanish Astrophysics III by : Jesús Gallego
Download or read book Highlights of Spanish Astrophysics III written by Jesús Gallego and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the Proceedings of the Fifth Scientific Meeting of the Spanish Astronomical Society (Sociedad Espanola de Astronomfa, SEA). The meeting was held at the Universidad de Castilla La Mancha in Toledo, from September 9 to 13, 2002. The event brought together 219 participants who pre sented their latest results in many different subjects. In comparison with the previous scientific meetings of the Society, the numbers of oral talks and poster contributions (122 and 64, respectively) are rapidly increasing, confirming that the SEA conferences are becoming a point of reference to assess the interests and achievements of astrophysical research in Spain. During the meeting, the SEA made public the granting of the Prize to the Best Spanish Ph. D. Thesis in As tronomy and Astrophysics for the period 2000-2001 ex aequo to Dr. A. Zurita and Dr. E. Villaver. This is the second time that the SEA is awarding this prize, which aim is to encourage young spanish astrophysicists to pursue a high level scientific career. The Society is indebted to the Universidad de Castilla La Mancha, and, in particular, to the San Pedro Martir staff, for its hospitality. It is also indebted to the Local Organizing Committee for its dedication and the good atmosphere that prevailed at any moment, and to the Scientific Organizing Committee for its excel lent work.
Book Synopsis Physics of Active Galactic Nuclei by : Wolfgang J. Duschl
Download or read book Physics of Active Galactic Nuclei written by Wolfgang J. Duschl and published by Springer. This book was released on 1992 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The physical processes driving the different manifestations of the phe nomenon of active galactic nuclei have been studied extensively during the last decade. A major obstacle in all attempts to understand the relevant pro cesses has always been the wide range of frequencies over which significant fractions of the total power are emitted. During the last decade, orbiting telescopes and instrumental improvements for ground-based instrumenta tion provided the means for major advancements on the observational side. The organizers felt that it was timely to organize a meeting to discuss the impact of this new situation on the understanding of the relevant physical processes. More then 400 astrophysicists were interested in participating in the meeting, in spite of the constraints on overseas travel which were imposed in early 1991. Unfortunately only 220 participants could be hosted by the Max-Planck-Haus, the site of the 1991 Heidelberg conference. The meet ing was organized by Sonderforschungsbereich 328 "Evolution of Galaxies". During 5 sessions, most of which lasted for one day each, 47 invited and con tributed talks and 150 poster papers were given, most, but not all, of which are included in these proceedings. With a few exceptions the order of the written texts follows that of the oral contributions during the meeting. The arrangement of posters into the five sections was not always unambiguous. We hope to have placed them in the most appropriate sections, in which they are listed in alphabetical order.
Book Synopsis Variability of Blazars by : E. VALTAOJA (Ed)
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.
Book Synopsis Investigating Active Galactic Nuclei with Low Frequency Radio Observations by : Matthew Lazell
Download or read book Investigating Active Galactic Nuclei with Low Frequency Radio Observations written by Matthew Lazell and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Active Galactic Nuclei by : Ian Robson
Download or read book Active Galactic Nuclei written by Ian Robson and published by . This book was released on 1996-05-07 with total page 406 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.
Author :United States. Congress. House. Committee on Science and Technology. Subcommittee on Science, Research, and Technology Publisher : ISBN 13 : Total Pages :748 pages Book Rating :4.3/5 (121 download)
Book Synopsis 1984 National Science Foundation Authorization by : United States. Congress. House. Committee on Science and Technology. Subcommittee on Science, Research, and Technology
Download or read book 1984 National Science Foundation Authorization written by United States. Congress. House. Committee on Science and Technology. Subcommittee on Science, Research, and Technology and published by . This book was released on 1983 with total page 748 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Atacama Large Millimeter Array by :
Download or read book The Atacama Large Millimeter Array written by and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
