Download or read book Modeling of optical and ultraviolet polarization in active galactic nuclei written by René W. Goosmann and published by . This book was released on 2002 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Optical and Ultraviolet Polarization in Active Galactic Nuclei written by Rene W. Goosmann and published by . This book was released on 2002 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Time dependent Optical and UV Correlations in Active Galactic Nuclei written by Patricia Rojas Lobos and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active galactic nuclei (AGN) include the most powerful quasi-steady sources of energy known to date in the universe. Due to their distance, high brightness and small size, their inner regions are not directly resolvable with current telescopes. This is the reason why indirect techniques and theoretical models are needed to discern their structure. In this scenario the role of polarimetry is crucial. In the past it was the key method that led to the development of the Unified Model of AGN and in the future, it may give us new clues to probe unresolved AGN regions. In this thesis, I conducted radiative transfer simulations for continuous radiation of different inner regions of the AGN using the new technique of polarimetric reverberation mapping. This work has been inspired by the work of Gaskell et al. (2012). The goal of this research is to provide theoretical models of the different components of the AGN considering time-dependent polarized radiation. Scattering induced polarization has been modeled and different circumnuclear dust geometries have been explored. The results include the effects of clumpiness and different dust compositions. To further extend the model, the effects of additional extended ionized winds along the polar direction have also been explored as well as the putative equatorial scattering ring postulated to explain the polarization angle observed in pole-on AGN. The simulations were run using a time-dependent version of the STOKES code. It will be possible to extend this work in the future. Suggested future steps are including emission lines in the models, as well as more complexity in the geometry and distribution of dust and/or electrons in the scattering regions. This work will be important for taking advantage of systematic future observational data with good temporal sampling.
Download or read book Relativistic Jets from Active Galactic Nuclei written by Markus Boettcher and published by John Wiley and Sons. This book was released on 2012-02-13 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by a carefully selected consortium of researchers working in the field, this book fills the gap for an up-to-date summary of the observational and theoretical status. As such, this monograph includes all used wavelengths, from radio to gamma, the FERMI telescope, a history and theory refresher, and jets from gamma ray bursts. For astronomers, nuclear physicists, and plasmaphysicists.
Download or read book Astrophysics Of Quasi Stellar Objects And Active Galactic Nuclei written by Joseph S. Miller and published by University Science Books. This book was released on 1985 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Based on the 1984 Santa Cruz Astrophysics Workshop"--Verso t.p.
Download or read book Multi wavelength Studies of Active Galactic Nuclei on Parsec and Kiloparsec Scales written by Juan Carlos Algaba and published by . This book was released on 2010 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although the continua of radio-loud Active Galactic Nuclei (AGN) are typically dominated by synchrotron radiation over virtually the entire spectrum, it is not clear whether the radio and higher-frequency emission originate in the same or different parts of the jet. In some inhomogeneous synchrotron source models for blazars, the radio and UV-optical-IR (UVOIR) emission may be co-spatial, depending on the model parameters considered. Indeed, several different radio{u2013}optical correlations based on polarization data have been found recently, suggesting that the optical and radio polarization may be closely related, and that the corresponding emission regions may be cospatial. My joint analysis of optical and 15+22+43 GHz VLBA polarization data for a sample of about 40 AGNs shows that, after correction for the inferred VLBA core Faraday rotations, most BL Lac objects and some quasars have aligned VLBA-core and optical polarizations, although many quasars also show no obvious relationship between their VLBA-core and optical polarization angles. This apparently indicates that not all AGNs have co-spatial regions of optical and radio emission in their jets. However, another possibility was that some of the 15{u2013}43 GHz VLBA cores have Faraday rotations of the order of several tens of thousand of rad/m2, which were not properly fit using our three-frequency data due to n {u00D7} _ ambiguities in the observed polarization angles, leading to incorrect subtraction of the effects of the core Faraday rotation, and so incorrect {u2018}zero-wavelength{u2019} radio polarization angles. With this is mind, I obtained additional observations for 8 of the 40 AGN, this time at 12+15+22+24+43 GHz, chosen in such a way that we should be able to discern between various possible scenarios. My results indicate that, although some VLBI radio cores have comparatively high rotation measures, this cannot explain the misalignments found between the radio core and optical VLBI polarization angles. I performed a series of analyse to check if this could be explained by other physical processes or properties occurring in the AGN, such as degree of polarization, magnetic field intensity or presence of detectable {u2013}ray emission. No clear differences between the properties of sources with aligned and misaligned radio-core and optical polarization angles was found. The emission from AGN is mostly synchrotron in origin, making it natural that the degree of circular polarization (CP) is low, less than a percent. For this reason, the detection of CP is a non trivial task. However, using recently developed new techniques, I have performed circular polarization analysis on some of my sources. The results indicate that the degree of CP tends to increase with frequency, with the spectral index being either flat or inverted, _ _ +1, which can be explained with a Blandford-Königl jet model. Using the measured intensity, spectral indices and magnetic fields derived from the measured core shift, I have derived the degree of order of the magnetic field required to explain if this observed CP is generated by the synchrotron mechanism. The implied degrees of order of the magnetic field are too high in most cases for the CP to be synchrotron in origin, requiring a substantial (possible dominant) contribution from Faraday conversion of linear to circular polarizaton. A kilo-Parsec multiwavelength study has also been performed on the source PKS 0521{u2013}365. This AGN has been classified as a HYMOR (Hybrid morphology radio source) and has a jet which is clearly detectable over a wide frequency band, ranging from radio to X-rays. This has allowed me to perform a study of its physical properties over radio, near infra-red, optical and X-rays bands, thus obtaining valuable information about its morphology, spectral energy distribution and magnetic field. The data here supports the hypothesis that PKS0521-36 is intermediate between an FRI and FRII source, agreeing with unified scenarios in which the differences between these classes can be understood on a physical basis.
Download or read book Active Galactic Nuclei written by Volker Beckmann and published by John Wiley & Sons. This book was released on 2013-08-29 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active Galactic Nuclei This AGN textbook gives an overview on the current knowledge of the Active Galacitc Nuclei phenomenon. The spectral energy distribution will be discussed, pointing out what can be observed in different wavebands. The different physical models are presented together with formula important for the understanding of AGN physics. Furthermore, the authors discuss the AGN with respect to its environment, host galaxy, feedback in galaxies and in clusters of galaxies, variability, etc. and finally the cosmological evolution of the AGN phenomenon. This book includes phenomena based on new results in the X-Ray and gamma-ray domain from new telescopes such as Chandra, XMM-Newton, the Fermi Gamma-Ray Space Telescope, and the VHE regime not mentioned so far in AGN books. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities. From the contents: The observational picture of AGN Radiative processes The central engine AGN types and unification AGN through the electromagnetic spectrum AGN variability Environment Quasars and cosmology Formation, evolution and the ultimate fate of AGN What we do not know (yet)
Download or read book Models of the Continuum Polarization in Active Galactic Nuclei written by John Francis Kartje and published by . This book was released on 1995 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Complex Morphology of Radio quiet Active Galactic Nuclei written by Frédéric Marin and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: When probing the inner structures of unresolved astrophysical sources, spectropolarimetry has proven to be a solid tool, both independent and complementary to spectral and timing analyses. In this thesis, I theoretically explore the polarization of Active Galactic Nuclei (AGN), which are powered by accretion onto supermassive black holes and often reveal significant mass outflows. Their emission is strongly anisotropic and the standard model of AGN postulates that the anisotropy is caused by a confinement of the radiation in the funnel of an obscuring body of circumnuclear dust; the radiation is thus forced to escape along the funnel where it photo-ionizes conically shaped outflows. The asymmetrical configuration explains an observational dichotomy where AGN properties are characterized according to the observer's line-of-sight. However, AGN observations differ significantly from one waveband to another and the broadband validity of the unified model has to be tested by a method that gives strong constraints on the AGN morphology. In this thesis, I subsequently investigate how morphological and composition constraints on the different substructures in thermal, radio-quiet Active Galactic Nuclei can be deduced from optical, UV and X-ray polarization properties.
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 International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1020 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Literature 1985 Part 2 written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-12-14 with total page 1106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts aims to present a comprehensive documen tation ofthe literatme concerning all aspects of astronomy, astrophysics, and their border fields. lt is devoted to the recording, summarizing, and indexing of the relevant publications throughout the world. Astronomy and Astrophysics Abstracts is prepared by a special department of the Astronomisches Rechen-Institut under the auspices of the International Astronomical Union. Volume 40 records literatme published in 1985 and received before February 15, 1986. Some older documents which we received late and which arenot surveyed in earlier volumes are included too. We acknowledge with thanks contributions of our colleagues all over the world. We also express our gratitude to all organiza tions, observatories, and publishers which provide us with complimentary copies of their publications. Starting with Volume 33, all the recording, correction, and data processing work was dorre by means of computers. The recording was dorre by om technical staff members Ms. Helga Ballmann, Ms. Mona El-Choura (t), Ms. Monika Kohl, Ms. Sylvia Matyssek. Ms. Karirr Burkhardt, Ms. Susanne Schlötelbmg, Mr. Mar tin Schlötelburg, and Mr. Stefan Wagner supported om task by careful proof reading. lt is a pleasure to thank them all for their encomagement.
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 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 Astronomy and Astrophysics Abstracts written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-12-14 with total page 1180 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the reviews: Astronomy and Astrophysics Abstracts has appeared in semi-annual volumes since 1969 and it has already become one of the fundamental publications in the fields of astronomy, astrophysics and neighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. ... The abstracts are classified under more than hundred subject categories, thus permitting a quick survey of the whole extended material. The AAA is a valuable and important publication for all students and scientists working in the fields of astronomy and related sciences. As such it represents a necessary ingredient of any astronomical library all over the world." Space Science Reviews #1 "Dividing the whole field plus related subjects into 108 categories, each work is numbered and most are accompanied by brief abstracts. Fairly comprehensive cross-referencing links relevant papers to more than one category, and exhaustive author and subject indices are to be found at the back, making the catalogues easy to use. The series appears to be so complete in its coverage and always less than a year out of date that I shall certainly have to make a little more space on those shelves for future volumes." The Observatory Magazine #1
Download or read book Astrophysical Spectropolarimetry written by J. Trujillo-Bueno and published by Cambridge University Press. This book was released on 2002 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: The polarization of light is the key to obtaining a wealth of essential information that lies encoded in the electromagnetic radiation from cosmic objects. Spectropolarimetry and imaging polarimetry provide powerful diagnostics of the physical conditions in astrophysical plasmas, which cannot be obtained via conventional spectroscopy. Whilst its application to other fields of astrophysics is still at an early stage of development, spectropolarimetry is being used with great success in solar physics. The book contains the lectures delivered at the XII Canary Islands Winter School of Astrophysics. Written by eight prestigious astrophysics researchers, it covers the physics of polarization, polarized radiation diagnostics of solar magnetic fields, stellar magnetic fields, polarization insights for active galactic nuclei, compact objects and accretion disks, astronomical masers and their polarization, infrared-submillimeter spectropolarimetry, and instrumentation for astrophysical spectropolarimetry. This timely volume will provide graduate students and researchers with an unprecedented introduction to the field of Astrophysical Spectropolarimetry.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
