X Ray And Multiwavelength Studies Of Active Galactic Nuclei From Large Area Sky Surveys
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X Ray And Multiwavelength Studies Of Active Galactic Nuclei From Large Area Sky Surveys
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Author : Jianfeng Wu
language : en
Publisher:
Release Date : 2012
X Ray And Multiwavelength Studies Of Active Galactic Nuclei From Large Area Sky Surveys written by Jianfeng Wu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Active galactic nuclei (AGNs) are ideal laboratories for fundamental physics and cosmology. Our knowledge of AGNs has been greatly advanced during the past decades thanks to the unprecedentedly powerful X-ray missions (e.g., Chandra, XMM-Newton, and Swift) and modern large area surveys in the optical/UV band (e.g., the Sloan Digital Sky Survey; SDSS). Studies on the relation between multiwavelength properties of AGNs can reveal the physics of AGN accretion process. In this dissertation, I mainly study the relation between the AGN X-ray properties and their optical/UV spectral properties on emission lines, absorption lines and continuum. I also investigate the X-ray properties of AGNs with extreme radio properties in the early Universe. (1) We studied the X-ray properties of a class of radio-quiet SDSS quasars with weak broad emission lines (weak-line quasars; WLQs). Although the WLQ population shows diverse X-ray properties, they have an excess of X-ray weak sources. Besides having weak emission lines, the X-ray weak WLQs generally show other unusual UV emission-line properties similar to those of the remarkable X-ray weak quasar PHL 1811 (e.g., highly blueshifted C IV lines, weak semi-forbidden lines, and strong UV Fe emission). They are classified as "PHL 1811 analogs". The X-ray weak WLQs also show a harder X-ray spectrum, while the WLQ with normal X-ray brightness have similar X-ray spectral properties to those of typical quasars. We proposed an AGN geometry which can potentially unify the X-ray weak and X-ray normal WLQ populations via orientation effect. The infrared-to-UV spectral energy distributions (SEDs) of X-ray weak and X-ray normal WLQs have consistent SEDs with those for typical quasars, which disfavors the BL Lac-like scenario for the nature of these quasars (Chapters 2 and 3). (2) We have led the best X-ray study to date on quasars with intermediate-width absorption lines (mini-BALs). We found the X-ray brightness of mini-BAL quasars are more close to those of typical quasars than to BAL quasars (which are generally X-ray weak), showing they do not have substantial X-ray absorption. Strong correlations were found between the X-ray brightness and UV absorption parameters, e.g., the absorption strength and maximum outflow velocity. We further proposed new UV absorption parameters which better correlate with the X-ray properties than existing parameters do (Chapter 4). (3) We studied the relation between the optical/UV luminosity and X-ray luminosity (quantified by the alpha_ox parameter) for the most-luminous quasars over a wide range of redshifts. Our correlation analyses provide better constraints on the alpha_ox-UV luminosity correlation. We have also verified that the alpha_ox parameter does not significantly evolve with redshift. We provide the individual and composite mid-infrared-to-UV SEDs for the most-luminous quasars. (Chapter 5). (4) We presented the X-ray and multiwavelength properties of the highly radio-loud quasars (HRLQs) at z > 4. Our HRLQs show a significant enhancement of X-ray emission over those HRLQs at lower redshift with similar optical/UV and radio luminosities, suggesting that the jet-linked X-ray emission mechanism in the early universe may differ from that in the more evolved universe. The optical/UV emission-line strength of RLQs are correlated with radio loudness, but not with relative X-ray brightness. Our HRLQs generally follow the anti-correlation between radio loudness and X-ray power-law photon index. We also studied the broad-band SEDs of HRLQs. Some HRLQs have an excess of mid-infrared emission which may originate from the jet synchrotron emission. None of our z > 4 HRLQs is detected by the Fermi LAT two-year survey (Chapter 6).
Active Galactic Nuclei Studies In Cosmic X Ray Survey Fields
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Author : Qingling Ni
language : en
Publisher:
Release Date : 2021
Active Galactic Nuclei Studies In Cosmic X Ray Survey Fields written by Qingling Ni and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with categories.
X-ray surveys are an effective way to study growing supermassive black holes (SMBHs) in galaxy centers, as actively accreting SMBHs manifest themselves as active galactic nuclei (AGN) that can be observed in the X-ray in most cases. Through studying AGNs in X-ray survey fields that have extensive multiwavelength data coverage, we can probe how SMBH growth links with their host galaxies over cosmic history. Previously, researchers mainly linked SMBH growth with stellar mass (M⋆) or star formation rate (SFR). In this dissertation, we utilize morphological information to show that among star-forming (SF) galaxies, long-term average SMBH accretion rate (BHAR) relates to host-galaxy compactness (Chapter 2). We found that the relation between BHAR and host-galaxy compactness is more fundamental than the relation between BHAR and M⋆ or SFR (Chapter 3). This dissertation also provides key results from the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS), which will benefit studies of SMBH growth in the next decade with a large sample of AGNs that have superb multiwavelength data. The detection of X-ray point sources in two of the XMM-SERVS survey fields is presented in Chapter 4. In Chapter 5, multiwavelength counterpart identification, photometric-redshift calculation, and source classification for X-ray sources in the XMM-SERVS survey fields are presented; most of the X-ray point-like sources detected are classified as AGNs, showing SMBH growth over the full range of cosmic environments. A Hyper Suprime-Cam (HSC) forced-photometry catalog that provides optical coverage for one of the XMM-SERVS survey fields is presented in Chapter 6. Apart from these works that focus on "Active Galactic Nuclei Studies in Cosmic X-ray Survey Fields", this dissertation also includes my other two first-author works in the appendices, where X-ray observational studies of weak-line quasars (WLQs) are presented. By studying these quasars with exceptional spectroscopic properties, we found good supporting evidence for optically thick inner accretion disks among quasars with high Eddington ratios.
New Horizons From Multi Wavelength Sky Surveys
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Author : Brian J. McLean
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
New Horizons From Multi Wavelength Sky Surveys written by Brian J. McLean and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
Large area sky surveys are now a reality in the radio, IR, optical and X-ray passbands. In the next few years, new surveys using optical, UV and IR mosaic cameras with high throughput digital detectors will expand the dynamic range and accuracy of photometry and astrometry of objects over a significant fraction of the entire sky. Parallel X-ray and radio surveys over the same areas will produce astronomical image and spectroscopic databases of unprecedented size and quality. The combined data sets will provide significant new constraints on star formation, stellar dynamics, Galactic structure, the evolution of galaxies and large scale structure, as well as new opportunities to identify rare objects in the solar system and the Galaxy. Large area surveys have formidable data acquisition, processing, archiving, and data distribution demands and this meeting provided a forum for sharing experiences amongst workers specializing in different wavebands as well as discussing how multiband observations can reveal fundamental relationships in our understanding of the Universe.
Multi Wavelength Population Studies Of Active Galactic Nuclei And Galaxies Using Primus And Aegis
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Author : Alexander John Mendez
language : en
Publisher:
Release Date : 2014
Multi Wavelength Population Studies Of Active Galactic Nuclei And Galaxies Using Primus And Aegis written by Alexander John Mendez and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
This dissertation uses large galaxy redshift surveys and multi-wavelength imaging to place observational constraints on the evolution of galaxies and the supermassive black holes that they host since the Universe was roughly half its current age. In the first chapter, we use data from the AEGIS survey to present quantitative morphological measurements of green valley galaxies, to constrain the mechanism(s) responsible for quenching star formation in this transition population and creating elliptical galaxies. We show that green galaxies are generally massive (M.) ~ 1010·5 M/[sun]) disk galaxies with high concentrations of light. We find that major mergers are not the dominant mechanism responsible for quenching star formation, and we find that either more mild external processes or internal secular processes play a crucial role in halting star formation. In the second chapter, we use data from the PRIMUS survey to investigate Spitzer/IRAC and X-ray AGN selection techniques in order to quantify the overlap, uniqueness, contamination, and completeness of each AGN selection. For roughly similar depth IR and X-ray data, we find that ~75% of IR-selected AGN are also identified as X-ray AGN. For the deepest X-ray data, this fraction increases to ~90%, indicating that at most ~10% of IR-selected AGN may be heavily obscured. While similar overall, the IR-AGN samples preferentially contain more luminous AGN, while the X-ray AGN samples identify AGN with a wider range of accretion rates, where the host galaxy light dominates at IR wavelengths. A more complete AGN sample is created by combining both IR and X-ray selected AGN. Finally, we present a clustering study of X-ray AGN, radio AGN and IR AGN selected AGN using spectroscopic redshifts from the PRIMUS and DEEP2 redshift surveys. Using the cross-correlation of AGN with dense galaxy samples, we find differences in the clustering of AGN selected at different wavelengths. However, we find no significant differences in the clustering of each AGN sample with matched galaxy samples that have the same redshift, stellar mass, and star formation rate distributions. The differences in the clustering of AGN selected at different wavelengths can therefore be explained by the clustering differences of their host populations
Multiwavelength Agn Surveys
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Author : R. MAIOLINO (Ed)
language : en
Publisher: World Scientific
Release Date : 2004
Multiwavelength Agn Surveys written by R. MAIOLINO (Ed) and has been published by World Scientific this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Science categories.
The huge amount of data obtained by surveys in all wavebands, from radio to X-rays, has allowed major progress in the understanding of Active Galactic Nuclei and of their cosmic evolution. This book contains the proceedings of a conference intended to give a broad overview of the recent results obtained by recent AGN surveys over the whole electromagnetic spectrum. Topics which were discussed during the conference and are included in this volume are: AGN evolution, contribution to the cosmic background, AGN luminosity functions in different wavebands, multiwavelength properties of AGN, unified model and unconventional AGN, connection with the host galaxies, co-evolution of AGN and galaxies, implications for the local density of supermassive black holes. Future AGN surveys planned with forthcoming new observational facilities are also included.The proceedings have been selected for coverage in: ? Index to Scientific & Technical Proceedings? (ISTP? / ISI Proceedings)? Index to Scientific & Technical Proceedings (ISTP CDROM version / ISI Proceedings)? CC Proceedings ? Engineering & Physical Sciences
Physics Of Active Galactic Nuclei At All Scales
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Author : Danielle Alloin
language : en
Publisher: Springer
Release Date : 2006-09-07
Physics Of Active Galactic Nuclei At All Scales written by Danielle Alloin and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006-09-07 with Science categories.
This book contains a collection of lecture notes written by recognized experts in the field of Active Galactic Nuclei (AGN). The collection is aimed at providing both an introduction and at the same time an overview of the state-of-the-art of AGN research. This book also addresses the still not entirely understood link of an AGN with its host galaxy and also the related question of the birth and growth of massive black holes in the Universe.
Frontiers Of X Ray Astronomy
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Author : A. C. Fabian
language : en
Publisher: Cambridge University Press
Release Date : 2004-07-08
Frontiers Of X Ray Astronomy written by A. C. Fabian and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004-07-08 with Science categories.
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.
The Interplay Among Black Holes Stars And Ism In Galactic Nuclei Iau S222
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Author : International Astronomical Union. Symposium
language : en
Publisher: Cambridge University Press
Release Date : 2004
The Interplay Among Black Holes Stars And Ism In Galactic Nuclei Iau S222 written by International Astronomical Union. Symposium and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Science categories.
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.
The Multi Messenger Approach To High Energy Gamma Ray Sources
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Author : Josep M. Paredes
language : en
Publisher: Springer Science & Business Media
Release Date : 2007-11-12
The Multi Messenger Approach To High Energy Gamma Ray Sources written by Josep M. Paredes and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-11-12 with Science categories.
This book provides a theoretical and observational overview of the state of the art of gamma-ray astrophysics, and their impact and connection with the physics of cosmic rays and neutrinos. With the aim of shedding new and fresh light on the problem of the nature of the gamma-ray sources, particularly those yet unidentified, this book summarizes contributions to a workshop that continues today.
Multiwavelength Agn Surveys Proceedings Of The Guillermo Haro Conference 2003
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Author :
language : en
Publisher:
Release Date : 2004
Multiwavelength Agn Surveys Proceedings Of The Guillermo Haro Conference 2003 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Active galactic nuclei categories.
The huge amount of data obtained by surveys in all wavebands, from radio to X-rays, has allowed major progress in the understanding of Active Galactic Nuclei and of their cosmic evolution. This book contains the proceedings of a conference intended to give a broad overview of the recent results obtained by recent AGN surveys over the whole electromagnetic spectrum. Topics which were discussed during the conference and are included in this volume are: AGN evolution, contribution to the cosmic background, AGN luminosity functions in different wavebands, multiwavelength properties of AGN, unified.