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:
Download or read book A Multi wavelength Study of Galaxy Clusters Hosting Radio Sources written by Joshua David Wing and published by . This book was released on 2013 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Galaxy clusters play an important role in understanding the formation of structure in the Universe and can be used to constrain cosmological parameters. Thousands of clusters are known in the nearby Universe, but few are confirmed at large distances. Remote clusters provide a view of the early Universe, and are important for studying galaxy evolution. Here, I describe a technique for finding distant clusters using bent, double-lobed radio galaxies. These radio sources are active galactic nuclei (AGN) that result from outflows of material surrounding supermassive black holes in the centers of massive galaxies. These outflows are typically bent as a result of the relative motion between the host galaxy and the surrounding hot gas that fills clusters. Using the Sloan Digital Sky Survey (SDSS) and the Faint Images of the Radio Sky at Twenty-centimeters ( FIRST ) survey, I determine the frequency with which bent radio sources are associated with rich galaxy clusters in the nearby Universe (z 0.5), as compared to non-bent radio sources. I find that 60% of bent radio sources are located in rich cluster environments, compared to 10 - 20% of non-bent radio sources. Therefore, bent radio sources are efficient tracers for clusters and are useful as beacons of clusters at large distances. Bent radio sources may achieve their morphologies through large-scale cluster mergers that set the intracluster medium (ICM) in motion. Using a suite of substructure tests, I determine the significance of optical substructure in clusters containing radio sources. I find no preference for substructure in clusters with bent double-lobed sources compared to other types of radio sources, indicating that bent sources will not necessarily preferentially select clusters undergoing recent large-scale mergers. Having established that bent radio sources efficiently locate clusters, I have obtained deep, follow-up observations at optical and near-infrared wavelengths to uncover associated distant cluster candidates. In addition, a large Spitzer Space Telescope survey is underway to observe all bent sources not detected in the SDSS. Follow-up observations reveal a large number of high-redshift candidates. Further study of these objects will lend insight into galaxy formation and evolution and feedback between an AGN and its environment at high-redshift for clusters with a range of masses.
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 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 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 Multi Wavelength Continuum Emission of AGN written by T.J.-L. Courvoisier and published by Springer. This book was released on 1994-05-14 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active Galactic Nuclei radiate over the electro-magnetic spectrum from radio waves to gamma rays. Understanding the physics of these objects therefore requires the synthesis of results from many different domains of Astronomy. It was the aim of the conference "Active Galactic Nuclei across the Electromagnetic Spectrum" to provide a forum where this exchange could take place. Some 300 astronomers participated to the conference, 250 of them presented results either as oral papers or in the form of posters. Observations in all domains of the electro magnetic spectrum in which astronomical observations can be made from the ground or from space were presented. Many theoretical contributions were also given. There has been a tremendous growth in the number and quality of Astronomical obser vations in many spectral domains over the past several years. Students of Active Galactic Nuclei have been particularly keen to make use of the available facilities (both space born and on the ground), often in a very organised way, in order to obtain repeated simultane ous data covering large bands of the spectrum. This approach has produced a qualitatively new set of data for understanding the physics of Active Galactic Nuclei. The task of the meeting was to review this data in a coherent way.
Download or read book AGN and Their Environment written by Hora D. Mishra and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Merging Processes in Galaxy Clusters written by L. Feretti and published by Springer Science & Business Media. This book was released on 2006-04-18 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mergers are the mechanisms by which galaxy clusters are assembled through the hierarchical growth of smaller clusters and groups. Major cluster mergers are the most energetic events in the Universe since the Big Bang. Many of the observed properties of clusters depend on the physics of the merging process. These include substructure, shock, intra cluster plasma temperature and entropy structure, mixing of heavy elements within the intra cluster medium, acceleration of high-energy particles, formation of radio halos and the effects on the galaxy radio emission. This book reviews our current understanding of cluster merging from an observational and theoretical perspective, and is appropriate for both graduate students and researchers in the field.
Download or read book On the Diffuse Non thermal Emission from Galaxy Clusters written by Julius Donnert and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Active Galactic Nuclei written by Volker Beckmann and published by John Wiley & Sons. This book was released on 2012-09-24 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 Multiwavelength Observations of Clusters of Galaxies and the Role of Cluster Mergers written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Some clusters of galaxies have been identified as powerful sources of non-thermal radiation, from the radio to X-ray wavelengths. The classical models proposed for the explanation of this radiation usually require large energy densities in cosmic rays in the intracluster medium and magnetic fields much lower than those measured using the Faraday rotation. They study here the role that mergers of clusters of galaxies may play in the generation of the non-thermal radiation, and they seek for additional observable consequences of the model. They find that if hard X-rays and radio radiation are respectively interpreted as inverse Compton scattering (ICS) and synchrotron emission of relativistic electrons, large gamma ray fluxes are produced, and for the Coma cluster, where upper limits are available, these limits are exceeded. They also discuss an alternative and testable model that naturally solves the problems mentioned above.
Download or read book Galaxies at High Redshift and their Evolution over Cosmic Time IAU S319 written by Sugata Kaviraj and published by Cambridge University Press. This book was released on 2016-09-15 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: IAU Symposium 319 was the largest galaxy evolution meeting at the IAU General Assembly in 2015. This volume presents a summary of the current state of the art in galaxy evolution studies, and provides a perspective on future large spectro-photometric surveys which will become available in the next decade. Topics covered include the emergence of galaxies and their constituent black holes during the first few billion years, the evolving interstellar medium as seen through modern instrumentation like Herschel, Planck and ALMA, and a look ahead to future ground- and space-based instruments that will become the workhorse facilities of the next decade, such as JWST and the SKA precursors. This volume will appeal to those who are interested in the formation and evolution of galaxies over cosmic time, as well as those who are active in developing, or on the science teams for, new astronomical instrumentation.
Download or read book Nonthermal Emission from Galaxy Clusters written by and published by . This book was released on 2015 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxy clusters are the most massive gravitationally-bound objects in the universe. The bulk of the mass in a cluster is dark matter, while the dominant baryonic component is a thermal, X-ray emitting plasma. Radio observations of diffuse synchrotron emission indicate that galaxy clusters host a population of cosmic rays; however, the nature of this nonthermal component is not well-understood. In this dissertation, I investigate three sources of nonthermal emission in galaxy clusters. The first is star formation in galaxies, which is correlated to gamma-ray emission. I derive lower limits on the gamma-ray emission for nearby clusters by considering the emission from star formation in cluster galaxies. These lower limits sit about an order of magnitude below current upper limits on gamma rays in clusters and will be an important contributor to gamma-ray emission as upper limits improve over time. Dark matter annihilation, which produces relativistic particles that can result in a broad spectrum of emission in cluster environments, is another source of nonthermal emission. I use nondetections and marginal detections of diffuse radio emission in clusters to constrain dark matter annihilation. I derive limits on the annihilation cross section that are competitive with limits from the nondetection of gamma rays in clusters and show that the best objects for study in the radio are different than those in gamma rays, indicating that dark matter searches in the radio can be complementary to searches in other energy bands. I also investigate the cosmic ray population in the merging cluster A2319, which hosts a previously detected radio halo. I present new observations which reveal a two-component radio halo: a 2 Mpc region that extends far past the observable X-ray emission, and an 800 kpc "core" that is bounded by the X-ray cold front. I speculate on the origins of this structure, and show that a hadronic origin for this radio halo is disfavored. Finally, I discuss current ideas and future telescopes that will clarify and deepen our understanding of nonthermal emission in clusters.
Download or read book Clusters of Galaxies Physics and Cosmology written by Andrei M. Bykov and published by Springer. This book was released on 2020-10-31 with total page 535 pages. Available in PDF, EPUB and Kindle. Book excerpt: Clusters of galaxies are large assemblies of galaxies, hot gas and dark matter bound together by gravity. Galaxy clusters are now one of the most important cosmological probes to test the standard cosmological models. Constraints on the Dark Energy equation of state from the cluster number density measurements, deviations from the Gaussian perturbation models, the Sunyaev-Zeldovich effect as well as the dark matter proles are among the issues to be studied with clusters. The baryonic composition of clusters is dominated by hot gas that is in quasi-hydrostatic equilibrium within the dark matter-dominated gravitational potential well of the cluster. The hot gas is visible through spatially extended thermal X-ray emission, and it has been studied extensively both for assessing its physical properties and as a tracer of the large-scale structure of the Universe. Magnetic fields as well as a number of non-thermal plasma processes play a role in clusters of galaxies as we observe from radioastronomical observations. The goal of this volume is to review these processes and to investigate how they are interlinked. Overall, these papers provide a timely and comprehensive review of the multi-wavelength observations and theoretical understanding of clusters of galaxies in the cosmological context. Thus, the volume will be particularly useful to postgraduate students and researchers active in various areas of astrophysics and space science. Originally published in Space Science Reviews in the Topical Collection "Clusters of Galaxies: Physics and Cosmology"
Download or read book NgVLA written by Eric James Murphy and published by . This book was released on 2018 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Physics and Evolution of Active Galactic Nuclei written by Hagai Netzer and published by Cambridge University Press. This book was released on 2013-09-16 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive introduction to the theory underpinning our study of active galactic nuclei and the ways we observe them.
Download or read book Regulation of Star Formation Amidst Heating and Cooling in Galaxies and Galaxy Clusters written by Sravani Vaddi and published by . This book was released on 2016 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Galaxy clusters are the largest gravitationally bound systems in the Universe and often host the largest galaxies (known as the brightest cluster galaxies (BCG)) at its centers. These BCG’s are embedded in hot 1-10 keV X-ray gas. A subset of galaxy clusters known as cool-core clusters show sharply peaked X-ray emission and high central densities, demonstrating cooling of the surrounding halo gas in timescales much shorter than a Hubble time. These observations led to the development of a simple cooling flow model. In the absence of an external heating process, a cooling flow model predicts that the hot intracluster medium gas in these dense cores would hydrostatically cool, generating cooling flows in the center of the cluster. This cooled gas will eventually collapse to form stars and contribute to the bulk of galaxy mass. The rates of star formation actually observed in the clusters however are far less than predicted by the cooling flow model, suggesting a non-gravitational heating source. Active galactic nuclei (AGN), galaxies hosting a supermassive black hole that ejects outflows via accretion, is currently the leading heating mechanism (referred to as AGN feedback) explaining the observed deficit in the star formation rates. AGN feedback also offers an elegant explanation to the observed black hole and galaxy co- evolution. Much of the evidence for AGN feedback has been obtained from studies focussed on galaxy clusters and luminous massive systems with little evidence that it occurs in more typical systems in the local universe. Our research investigates this less explored area to address the importance of AGN heating in the regulation of star formation in typical early type galaxies in the local universe. We selected a sample of 200+ early type, low redshift galaxies and carried out a multiple wavelength study using archival observed in the UV, IR and radio. Our results suggest that early type galaxies in the current epoch are rarely powerful AGN and AGN feedback is constrained to be low in our sample of low redshift, typical early type galaxies. Although heating from the AGN is powerful enough to suppress the cooling of the hot gas, it does not completely offset gas cooling at all times and substantial cooler gas exists in the cores of some galaxy clusters (cool-core clusters), the gas properties of which are not explained by AGN heating models alone. The second part of our research focuses on unravelling the mystery of the unknown heating source regulating star formation in galaxy clusters. We have obtained deep FUV spectroscopy using the HST cosmic origins spectrograph of two cool-core clusters A2597 and Zw3146. FUV spectral lines provide the much needed diagnostics capable of discriminating between various heating models, which was difficult with the standard optical line diagnostics. We investigate several heating/ionization mechanisms namely stellar photoionization, AGN photoionization, and shock heating. We use pre-run Mappings III photoionization code results to model the ionizing radiation field. In general, we notice that there is no one single model that provides a satisfactory explanation for the ionization state of gas. How- ever, we show that stellar and AGN photoionization alone are not enough to ionize the nebula in A2597 and speculate that, shock heating is the likely ionizing source."--Abstract.
