Download or read book Radio Recombination Lines in Quasars written by Edward James Wadiak and published by . This book was released on 1983 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Search for Radio Recombination Lines from Galaxies and Quasars written by E. Churchwell and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radio Recombination Lines written by P.A. Shaver and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since their first detection 15 years ago, radio recombination lines from several elements have been observed in a wide variety of objects including HII regions, planetary nebulae, molecular clouds, the diffuse interstellar medium, and recently, other galaxies. The observations span almost the entire range from 0.1 to 100 GHz, and employ both single djsh and aperture synthesis techniques. The theory of radio recombination lines has also advanced strongly, to the point where it is perhaps one of the best-understood in astro physics. In a parallel development, it has become possible over the last decade to study these same highly-excited atoms in the laboratory; this work provides further confirmation of the theoretical framework. However there has been continuing controversy over the astrophysical interpre tation of radio recombination line observations, especially regarding the role of stimulated emission. A workshop was held in Ottawa on 24-25 August, 1979, bringing together many of the active scientists to review the field and discuss these questions of interpretation. A broad concensus has emerged: the subtleties of the line-formation process are understood, and the conditions under which reliable in formation can easily be extracted from the line measurements are known. It thus appears likely that the emphasis will shift increasingly from the study of the line phenomenon itself to further application in other areas of astrophysics, ranging from physical processes in plasmas (temperatures, densities, ionization structure), to the large-scale properties of our galaxy (abundances, kinematics, structure), and studies of extragalactic systems.
Download or read book Intrinsic Absorption Lines in Radio selected Quasars written by Gordon Todd Richards and published by . This book was released on 2000 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radio Recombination Lines 25 Years of Investigation written by Mark Gordon and published by Springer Science & Business Media. This book was released on 1990-06-30 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: Text no 1 Radio Recombination Lines (RRLs), discovered in the USSR in 1964, have become a powerful research tool for astronomers. Available throughout the radio spectrum, these lines carry information regarding the density, temperature, turbulence and velocity of thermal plasmas. Their very existance shows the presence of thermal gas. They also can carry information regarding magnetic fields if Zeeman splitting were to be detected. Containing the proceedings of an IAU Colloquium celebrating the 25th anniversary of their detection, this volume tells us what has happened since. It contains the story of the detection of RRLs and reviews of many areas of physics of the interstellargas from which stars form, HII regions excited by newly formed stars, planetary nebulae involving dying stars, and the structure of our Milky Way and other galaxies reflecting the large-scale morphology of the star formation process. In addition there is an article describing modern laboratory studies of Rydberg atoms to probe the basic physics of atomic structure, and articles describing the theory of collisions and radiation upon Rydberg atoms leading to observate effects to be used as diagnostic tools in astromony. This book focuses on the 25 years of astronomical research with radio recombination lines (RRLs) since their discovery in 1965. It covers a wide range of topics: papers dealing with research into Rydberg atoms both in the laboratory and in the interstellar medium of our galaxy and others; papers on the interaction of radiation and atomic systems, as well as with the effects of inadiabatic collisions between these atoms and both ions and electrons. It deals with astronomical observations of atoms with `diameters' ranging from 0.08 to 50 mum a size factor of 625. It deals with RRLs in absorption, in emission and as true masers. And it deals with plasmas with temperatures ranging from 10 to greater than 104 kelvins, and with an even greater range of volume densities. Much new work is reported, including low frequency RRLs discovered in 1980 and the maser RRLs from the star MWC349, discovered in 1989. The advent of aperture synthesis telescopes and large single-element telescopes have made possible RRL studies with high angular resolution. The sum total of the work reported here will make the volume a platform from which to search new horizons in RRL research.
Download or read book Structure and Kinematics of Quasar Broad Line Regions written by C. Martin Gaskell and published by . This book was released on 1999 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Proceedings of a March 1998 meeting, with papers in sections on general considerations and photoionization modeling, profile variation and reverberation mapping, flows, disks, narrow-line Seyfert 1 galaxies, the intermediate line region and lower-velocity gas, X-ray warm absorber and dust, and unified theories and connections with extended emission. Specific topics include spectral variability of NGC 4151 during 1990 and disk emission line issues. Lacks a subject index. The editor is associated with the University of Nebraska. Annotation c. Book News, Inc., Portland, OR (booknews.com)
Download or read book Galactic and Extragalactic Radio Astronomy written by E. Bouton and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 715 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galactic and Extragalactic Radio Astronomy is a fundamental text for graduate students and professional astronomers and covers all aspects of radio astronomy beyond the solar system. Each chapter is written by a renowned expert in the field and contains a review of a particular area of radio astronomy and presents the latest observations and interpretations as well as an extensive view of the literature (as of 1988). Topics covered include: galactic continuum emission, HII regions, the diffuse interstellar medium, interstellar molecules, astronomical masers, neutral hydrogen, the galactic center, radio stars, supernova remnants, pulsars, extragalactic hydrogen, radio galaxies and quasars, the microwave background, and cosmological radio sources.
Download or read book Quasars Their Importance in Astronomy and Physics written by Franz Daniel Kahn and published by . This book was released on 1967 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectrophotometry of Intermediate and High redshift Quasars written by C. Martin Gaskell and published by . This book was released on 1981 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Broad and Narrow Intrinsic Absorption in Quasars as it Relates to Outflows Orientation and Radio Properties written by Robert Bernard Stone and published by . This book was released on 2018 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work provides evidence that a large fraction of narrow absorption lines (NALs) seen along the line of sight to distant quasars are due to accretion disk winds, while also seeking to understand the relationship between NALs and certain quasar-intrinsic properties. We extend the results from past work in the literature with velocity distributions (dN/d[beta]) of ~ 108,000 NALs from a sample of ~ 58,000 Sloan Digital Sky Survey (SDSS) quasars. The primary results of this work are summarized as follows: (1) the velocity distribution of NALs is independent of radio loudness (or even detection) once marginalized by optical/UV luminosity; (2) there are significant differences in the number and distribution of NALs as a function of both radio spectral index and optical/UV luminosity and these two findings are not entirely interdependent; (3) improvements in quasar systemic redshift measurements, analysis of NALs in broad absorption line quasars, and differences in the NAL distribution as a combined function of optical luminosity and radio spectral index---together provide evidence that a significant portion of NALs are due to quasar outflows; (4) the results are consistent with standard models of accretion disk winds governed by the L_UV-[alpha]_ox relationship and line-of-sight orientation indicated by radio spectral index; and (5) possibly supports the magnetically arrested disk model as an explanation for the semi-stochastic nature of strong radio emission in a fraction of quasars.
Download or read book Radio Recombination Line Observations of HII Regions and Planetary Nebulae written by Pieter Roelf Roelfsema and published by . This book was released on 1987 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Physics and Chemistry of the Interstellar Medium written by A. G. G. M. Tielens and published by Cambridge University Press. This book was released on 2005-08-25 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publisher Description
Download or read book Mean and Extreme Radio Properties of Quasars and the Origin of Radio Emission written by Rachael Marie Kratzer and published by . This book was released on 2014 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: I investigate the evolution of both the radio-loud fraction (RLF) and, using a stacking analysis, the mean radio-loudness of quasars. I consider how these values evolve as a function of redshift and luminosity, black hole (BH) mass and accretion rate, and parameters related to the dominance of a wind in the broad emission line region. I match the FIRST source catalog to samples of luminous quasars (both spectroscopic and photometric) primarily from the Sloan Digital Sky Survey. After accounting for catastrophic errors in BH mass estimates at high-redshift, I find that both the RLF and the mean radio-loudness increase for increasing BH mass and decreasing accretion rate. Similarly, both the RLF and mean radio-loudness increase for quasars that are argued to have weaker radiation line-driven wind components of the broad emission line region. In agreement with past work, I find that the RLF increases with increasing optical luminosity and decreasing redshift while the mean radio-loudness evolves in the exact opposite manner. This difference in behavior in the L-z plane may indicate selection effects that bias an understanding of the evolution of the RLF; deeper surveys in the optical and radio are needed to resolve this discrepancy. Finally, I argue that radio-loud (RL) and radio-quiet (RQ) quasars may be parallel sequences. Only RQ quasars at one extreme of the distribution are likely to become RL through slight differences in spin and/or merger history.
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.
Download or read book Active Galactic Nuclei written by Professor R. D. Blandford and published by Springer. This book was released on 2013-12-14 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evidence for a quasar in the radio galaxy Cygnus A from observation of broad line emission written by Robert Antonucci and published by . This book was released on 1994 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Transport in Radio Galaxies and Quasars written by Philip E. Hardee and published by . This book was released on 1996 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:
