Download or read book Multiwavelength AGN Surveys and Studies IAU S304 written by Areg M. Mickaelian and published by Cambridge University Press. This book was released on 2014-08-21 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active galactic nuclei (AGN) are among the most interesting astrophysical objects in the Universe. IAU Symposium 304, dedicated to marking the centenary of B. E. Markarian's birth, addresses the most important questions in this area: understanding the possible evolutionary and/or physical connections between the different classes of AGN; the relation of AGN to their host galaxies; and understanding the true fraction of heavily obscured AGN in order to determine the true AGN luminosity function and its variation with redshift. This volume's topics include: historical spectral and colorimetric surveys, multiwavelength AGN surveys, AGN statistics, unification and other models of AGN, AGN feedback in galaxies and clusters, their host galaxies and environments, binary AGN and merging supermassive black holes, AGN variability, and future large projects. This fresh summary of AGN surveys is especially useful for researchers engaged in this exciting field and helping them plan for future surveys and observations.

Download or read book Multiwavelength AGN Surveys and Studies written by International Astronomical Union. Symposium and published by . This book was released on 2014 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiwavelength Agn Surveys Proceedings Of The Guillermo Haro Conference 2003 written by Raul Mujica and published by World Scientific. This book was released on 2004-10-12 with total page 459 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book X ray and Multiwavelength Studies of Active Galactic Nuclei from Large Area Sky Surveys written by Jianfeng Wu and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).

Download or read book Multiwavelength AGN Surveys written by R. MAIOLINO (Ed) and published by World Scientific. This book was released on 2004 with total page 459 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Multiwavelength Agn Surveys Proceedings of the Guillermo Haro Conference 2003 written by and published by . This book was released on 2004 with total page 459 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Multi wavelength Population Studies of Active Galactic Nuclei and Galaxies Using PRIMUS and AEGIS written by Alexander John Mendez and published by . This book was released on 2014 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Probing AGN Accretion Flows With Multi Wavelength Time Domain Observations written by Weixiang Yu and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: At UV/optical wavelengths, the luminosity of Active Galactic Nuclei (AGNs) varies stochastically on timescales ranging from hours to years. This stochastic variability originates from AGN's accretion disk and provides unique information about its inner workings. It has recently been shown that AGN UV/optical variability exhibits different characteristics at short and long timescales. This dissertation utilizes the approach of directly modeling AGN UV/optical light curves as a noise-driven damped harmonic oscillator (DHO) process. This approach enables us to connect short and long-term variability and probe the accretion flows in AGNs. The DHO process is a second-order continuous-time autoregressive moving-average process---a statistical model commonly used to forecast the stock market. We carry out two investigations in this study: 1) we apply the DHO model to 9́8 12,000 AGNs with 8-years-long ugriz light curves collected from the Sloan Digital Sky Survey (SDSS); 2) we repeat the process for 9́8 24,000 AGNs with combined gri light curves from SDSS and the PanSTARRS1 (PS1) survey. The distributions of DHO fits obtained in these two investigations are broadly consistent, demonstrating that AGNs occupy a unique part of the DHO parameter space. We find that: 1) the best-fit DHO parameters correlate with the probed rest-frame wavelength ([lambda] RF ) and the fundamental properties of our modeled AGNs; 2) the modeled long-term variability at [lambda] RF > 2800A might be contaminated by the Balmer diffuse continuum external to the accretion disk; 3) the long-term characteristic variability timescale extracted by the DHO exhibits a wavelength dependence that is closest to the theoretical prediction when compared to similar timescales extracted using other methods. We demonstrate that the DHO process is a viable choice for directly modeling AGN's UV/optical variability. The upcoming all-sky time-domain survey, Rubin Observatory's Legacy Survey of Space and Time (LSST), will benefit from this approach, given LSST's superior light curves.

Download or read book Multi Wavelength Continuum Emission of AGN written by International Astronomical Union. Symposium and published by Springer. This book was released on 1994-04-30 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Note: the title actually, but erroneously, shown on the dust jacket, cover, and title page is Multi-Wavelength Continuum Emission of AGN, which is really only the heading of the first section of the volume. Because the correct, but omitted, title subsumes the erroneous title, Book News uses it in order to most accurately establish the reach of the volume.) The proceedings, then, of IAU Symposium No. 159, held in Geneva, Switzerland, August-September 1993, contain almost all of the presentations given at the conference both as posters and as oral invited and contributed papers. They address topics in multi- wavelength continuum emission of AGN; new observations of AGN with specific instruments; variability; correlations between emission components; AGN physics and models; unified schemes and relations with other types of objects; continuum studies; emission processes; x-rays and higher energies; variability; radio emission (maps); line studies; disk structure and emission; and statistical studies and evolution. Annotation copyright by Book News, Inc., Portland, OR

Download or read book Multiwavelength Analyses of Mid Infrared Selected Active Galactic Nuclei written by Anson Lam and published by . This book was released on 2018 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: Traditional methods of identifying active galactic nuclei (AGNs) rely on UV and optical color criteria, but these methods exclude AGNs that are highly optically obscured by surrounding dust. This bias causes underestimates in the number of obscured AGNs in the Universe, and is problematic for our understanding of galaxy evolution and computing luminosity functions. Since much of the radiation absorbed by dust is re-radiated in the IR, mid-IR color selection provides a much more robust method of identifying AGNs that is not biased against highly dust obscured galaxies. The Wide-field Infrared Survey Explorer (WISE) has provided an all-sky mid-IR survey in four passbands, and the photometry from this catalog can be used to identify AGN candidates. We select AGNs from the catalog using a WISE $W1-W2>0.8$ color cut, and perform follow-up observations with the Keck DEIMOS optical spectrograph for redshift and emission line measurements. We spectroscopically confirm that mid-IR color selection does indeed identify obscured AGNs that are missed by the largest existing optical surveys, and targeted observations are necessary to find these objects. Combining WISE data with the AKARI far-IR all-sky catalog, we also perform SED analysis to characterize the physical properties of dusty AGNs and their surrounding obscuring medium. Using only photometry, we are able to extract a number of physical properties (ex. dust temperature and masses) without the need for time and resource-intensive spectroscopy. Finally, we test the effects of using different SED and color criteria to select different populations of AGNs from the 3D-HST catalog and compute their luminosity functions. We find that SED fitting can identify a large number of AGNs that are missed by traditional color selection methods, and this can potentially increase the sample size of AGNs available for analysis by several factors.

Download or read book Radio AGN Evolution with Low Frequency Radio Surveys written by Louise Moira Ker 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 Multiwavelength Studies of Ultra soft X ray AGN written by Elizabeth Maria Puchnarewicz and published by . This book was released on 1992 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Astronomical Data Analysis Software and Systems XIV written by Patrick L. Shopbell and published by . This book was released on 2005 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multi wavelength Observations of High Accretion Rate Type 1 Active Galactic Nuclei and Other Super Soft X ray Sources written by Mark Simpson and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of X-ray emission from AGN allows the investigation of the inner regions of their central engine. By understanding the processes taking place within AGN, many other areas of research will benefit, such as accretion and the formation and evolution of galaxies. This thesis begins by investigating the background AGN population of the serendipitous sources detected in a deep-look (~ 500 ks) of the XMM-Newton field of view surrounding 3C 273. The deep-look is created by mosaicing XMM-Newton EPIC calibration observations of 3C 273. Time averaged spectra of the 17 brightest X-ray sources are analysed. Cross-correlation of the X-ray sources with catalogues at other wavelengths is performed and unique candidate counterparts proposed. Classification of the X-ray sources is attempted and the background AGN population is discussed. A number of AGN have shown evidence of high-ionisation, high-velocity outflows in their X-ray spectra. These sources are believed to have a high-accretion rate at or near the Eddington limit. Six suspected high-accretion rate narrow line AGN observed with XMM-Newton are analysed and inspected for the presence of these outflows. No such outflows are detected. However, three of the targets did show evidence of mass loss in the form of a warm absorber. In addition, all of the sources appear to have a soft excess below ~2 keV. Finally, a search for the AGN population of super soft X-ray sources (SSXs) in the first and second XMM-Newton catalogues is performed. Hardness ratios are used to search for SSXs, which are defined as having a characteristic temperature, kT>~100 eV. Cross-correlation of the selected SSXs with catalogues at other wavelengths is performed, returning both Galactic and extragalactic candidate counterparts. For a small number of SSXs with previously unclassified optical candidate counterparts, optical spectroscopic observations were acquired. The analysis of these observations identified 5 previously unclassified AGN.

Download or read book Multiwavelength AGN Surveys written by and published by . This book was released on 2004 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiwavelength Detection of Cluster AGN written by Alison J. Klesman and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: We aim to study the effect of environment on the presence and fueling of Active Galactic Nuclei (AGN) in massive galaxy clusters. We first explore the use of different AGN detection techniques with the goal of selecting AGN across a broad range of luminosities, AGN/host galaxy flux ratios, and obscuration levels. We quantify the use of optical variability in comparison with X-ray detection and mid-IR power-law SED fitting to identify AGN in the GOODS-South field. We then analyze a sample of 12 galaxy clusters at redshifts 0.5

Download or read book Multi wavelength Studies of AGN Feedback and Non thermal Emission in Galaxy Clusters and Groups written by Thomas Pasini and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: