Download or read book The impact of the local environment on the properties of radio galaxies written by Elizabeth Pike Bozyan and published by . This book was released on 1985 with total page 984 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radio Galaxies and the Role of Environment written by Lu Shen and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes research performed in the field of observational astrophysics as part of the Observations of Redshift Evolution in Large Scale Environment (ORELSE) survey, an ongoing multi-wavelength imaging and spectroscopic campaign investigating galaxyevolution in the environments of large scale structures (LSSs) surrounding 16 known clusters at the redshift range of $0.6 [less than or equal to] z [less than or equal to] 1.3. The aim of this dissertation is to contextualize how environment influences galaxy evolution among radio-emitting galaxies and radio Active Galactic Nucleus (RAGN) in a wide dynamic range of environments over cosmic time. In each of the three main chapters I present a sample of radio galaxies and an analysis of the connection to their environments. In the first part of this dissertation I describe the context of radio galaxies, galaxy environments, and the current state of the ORELSE survey. This initial section will set the framework for the variety of studies presented in this thesis. In the second part of this dissertation I present three studies undertaken to investigate various aspects of radio galaxies and the role of there environments. The first of these studies is an investigation of radio galaxies that are cross-matched to spectroscopically-confirmed galaxies in the large scale structures in the five fields of the ORELSE survey. To appropriately classify radio galaxies and study the properties of them separately, a two stage classification method is designed, where radio galaxies are classified into three sub-classes: active galactic nucleus (AGN), Hybrid, and star-forming galaxy (SFG). AGN tend to be preferentially located in locally dense environments and in the cores of clusters/groups, while SFGs exhibit a strong preference for intermediate-density global environments, with these preferences persisting when comparing to galaxies of similar color and stellar mass. These result has important consequences for galaxy evolutionary scenarios, as these two types of galaxies are thought to be the beginning and the end of galaxy evolution. The second of these studies is an investigation of the quenching effect of radio AGN (RAGN) on their neighboring galaxies. In this study, an elevated fraction of quenched RAGN neighbors was found in the most dense local and cluster environments, compared to those of non-RAGN control samples matched to the RAGN population in colour, stellar mass, and local environment. This result suggests that RAGN residing within clusters might heat the intracluster medium (ICM) affecting both in situ star formation and any inflowing gas that remains in their neighbors. This work has important consequences for understanding AGN feedback out of their host galaxies, which is the subject of much debate among astronomers.The final study in this dissertation is a full investigation of the co-evolution of AGN and star formation in radio galaxies in eight ORELSE fields. This study was first motivated by the Hybrid population analyzed in the first study, whose properties suggested that they have coeval star-formation and AGN activity with high accretion efficiency. Combining radio with mid-infrared and far-infrared data available in the ORELSE survey, the AGN and star formation contributions to the total infrared luminosity are well constrained. I present evidence for AGN quenching of the star formation in a rapid timescale in an orbital motion around the clusters/groups. This result has important consequences for galaxy evolutionary scenarios by connecting the two processes that are difficult to separate observationally and are thought to be related.

Download or read book Literature 1986 Part 1 written by Prof. Dr. Roland Wielen and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 1122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radio Galaxies written by A. G. Pacholczyk and published by Elsevier. This book was released on 2014-06-20 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radio Galaxies: Radiation Transfer, Dynamics, Stability and Evolution of a Synchrotron Plasmon deals with the physics of a region in space containing magnetic field and thermal and relativistic particles (a plasmon). The synchrotron emission and absorption of this region are discussed, along with the properties of its spectrum; its linear and circular polarization; transfer of radiation through such a region; its dynamics and expansion; and interaction with external medium. Comprised of eight chapters, this volume explores the stability, turbulence, and acceleration of particles in a synchrotron plasmon as well as its application to the physics of radio galaxies. The discussion begins with a description of extragalactic radio sources and their properties, followed by an analysis of the emission and absorption of synchrotron radiation. Subsequent chapters focus on the transfer of polarized radiation in a magnetoactive plasma; hydromagnetics and hydromagnetic stability; confinement and structure of extended radio sources; and radio-tail galaxies. The book also considers compact radio sources before concluding with an evaluation of radio source theories. This monograph is addressed primarily to radio astronomers and graduate students working on the interpretation of observational data.

Download or read book The Physics of Extragalactic Radio Sources written by David De Young and published by University of Chicago Press. This book was released on 2002 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extragalactic radio sources are among the most unusual and spectacular objects in the universe, with sizes in excess of millions of light years, radiated energies over ten times those of normal galaxies, and a unique morphology. They reveal some of the most dramatic physical events ever seen and provide essential clues to the basic evolutionary tracks followed by all galaxies and groups of galaxies. In The Physics of Extragalactic Radio Sources, David De Young provides a clearly written overview of what is currently known about these objects. A unique feature of the book is De Young's emphasis on the physical processes associated with extragalactic radio sources: their evolution, their environment, and their use as probes to solve other astrophysical problems. He also makes extensive use of the large amount of data now available from observations at x-ray, optical, and radio wavelengths to illustrate his main points. The Physics of Extragalactic Radio Sources will be a comprehensive introduction to the field for graduate students and a useful summary for astrophysicists.

Download or read book A Complete Study of Radio Galaxies at Z 0 5 written by Peter David Herbert and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis I investigate the hosts and cluster environments of a sample of 41 radio galaxies between z = 0.4 and z = 0.6. I use spectroscopic data for a 24 object subsample to investigate their star formation histories via the strength of the 4000A break. I find that the higher radio luminosity or high excitation objects in the sample have evidence for young stellar populations, but the lower radio luminosity or low excitation objects do not. My investigations into the Fundamental Plane (FP) of 18 of the radio galaxies, using the same spectroscopic data as well as data from the literature, show that the Fanaroff- Riley type I objects (FRIs) lie on the FP of local radio galaxies once corrected for passive evolution but the Fanaroff-Riley type II objects (FRIIs) do not. I suggest that an evolution in the size of the host galaxies, aided by a combination of passive evolution and a mass-dependent evolution in the mass-to-light ratios, may explain the observed offsets. Finally, I use wide field multi-band imaging to investigate the cluster environments of the full z ~ 0.5 sample. I find that the environmental overdensity is positively correlated with the radio luminosity and observe a greater number of close companions around the FRIIs than the FRIs (albeit with only nine FRIs in the sample). The cluster environments of the radio galaxies with the greatest host luminosities show tentative evidence for an alignment between the major axis of a galaxy and that of its cluster, whilst there are hints that the objects with the highest radio luminosities have clusters whose major axis is aligned with the position angle of the radio jet. My results suggest a picture in which FRII type radio sources reside in particularly rich cluster environments at z ~ 0.5 but FRI type radio sources in less rich environments. The environment plays a key role in determining both the radio properties of the galaxy and the evolution of its host. The effect of the environment on the emission line properties and star formation histories of the galaxies leads to the overlap seen in the morphological and spectral properties of radio galaxies.

Download or read book High Energy Astrophysics written by Malcolm S. Longair and published by Cambridge University Press. This book was released on 2011-02-03 with total page 885 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing students with an in-depth account of the astrophysics of high energy phenomena in the Universe, the third edition of this well-established textbook is ideal for advanced undergraduate and beginning graduate courses in high energy astrophysics. Building on the concepts and techniques taught in standard undergraduate courses, this textbook provides the astronomical and astrophysical background for students to explore more advanced topics. Special emphasis is given to the underlying physical principles of high energy astrophysics, helping students understand the essential physics. The third edition has been completely rewritten, consolidating the previous editions into one volume. It covers the most recent discoveries in areas such as gamma-ray bursts, ultra-high energy cosmic rays and ultra-high energy gamma rays. The topics have been rearranged and streamlined to make them more applicable to a wide range of different astrophysical problems.

Download or read book Space Telescopes and Instrumentation 2012 written by Mark C. Clampin and published by . This book was released on 2012 with total page 1856 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of SPIE present the original research papers presented at SPIE conferences and other high-quality conferences in the broad-ranging fields of optics and photonics. These books provide prompt access to the latest innovations in research and technology in their respective fields. Proceedings of SPIE are among the most cited references in patent literature.

Download or read book Toward a New Level of Modeling of Environmental Effects on Galaxies written by Manuel Duarte and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies lie in a large panel of environments from isolated galaxies, to pairs, groups or clusters. The environment is expected to have an impact on galaxy properties such as morphology, stellar formation, metallicity\ldots. Some studies already tried to quantify the importance of the global environment (linked to the dark matter halo mass) and the local environment (galaxy position in the group). These studies have shown that the environment plays a minor role except for low mass galaxies. But the quantification of the environment is difficult since detected groups in redshift space (the only one accessible by the observer) are very elongated, making it difficult to extract spherical groups in real space. If these quantification errors are too important, environment effects will not be measured correctly. Moreover, other physical processes are at work inside groups whose relative roles are not well understood. For example, major or minor mergers (rich or poor in gas, between satellite galaxies, or after the decay of the orbit of a satellite onto the central galaxy by dynamical friction), rapid flybys harassing galaxies, stripping of the interstellar gas by ram pressure or of the gaseous reservoir by tidal forces. Although semi-analytical codes of galaxy formation from initial conditions of a LambdaCDM Universe fit well a large set of observed relations, there are still some discrepancies that might be possibly explained by a lack of correct physical recipes of environmental effects in these models. Our goal with this thesis is to have a detailed comprehension of the role of environment on galaxy properties, and finally determine the major physical processes in the modulation of these properties with both local and global environment. For this, an optimal extraction of galaxy groups from the projected phase space is necessary. We performed a study and re-implementation of some existing group finder to estimate their strengths and weaknesses in the detection of galaxy groups. A galaxy mock catalogue in redshift space, designed to mimic the primary spectroscopic sample of the SDSS survey was created to apply several galaxy group algorithms. An advantage is the already known membership that we can compare to galaxy groups extracted from redshift space. Semi-analytical codes of galaxy formation give us such galaxy catalogs we transformed to be coherent with the vision of an observer. With these mock catalogues, we tested the very popular Friends-of-Friends grouping algorithm. We determined the optimal linking lengths against the set of tests and optimal criterion we developed to judge the efficiency of an algorithm. It appears that this choice of linking lengths depends on the scientific goal to do with the group catalogue. A large part of the thesis consisted on the realization of a new grouping algorithm called MAGGIE (Models and Algorithm for Galaxy Groups, Interlopers and Environment), Bayesian and probabilistic. MAGGIE uses our priors acquired with analysis of cosmological simulations for large scale structure and of observations obtained from large galaxy surveys, to better constrain the selection of galaxy groups from redshift space. Comparison of MAGGIE with the FoF algorithm shows that MAGGIE is superior in avoiding the fragmentation of real space groups, the membership selection (completeness, reliability) and in the group properties (group mass, luminosity). The better performance of MAGGIE comes from its probabilistic nature, the use of astrophysical and cosmological priors, and the use of halo abundance matching technique linking central galaxy distributions (stellar mass or luminosity) to physical properties of dark matter halos. The future application of MAGGIE on galaxy surveys such as the Sloan Digital Sky Survey or the deeper Galaxy and Mass Assembly, taking care of their own observational problems, should improve our understanding of the modulation of galaxy properties with their global and local environments and physical processes operating inside galaxy groups.

Download or read book Literature 1997 Part 1 written by Astronomisches Rechen-InstitutARI and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1746 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts is devoted to the recording, summarizing and indexing of astronomical publications throughout the world. Two volumes are scheduled to appear per year. Volume 67 records 10,903 papers covering besides the classical fields of astronomy and astrophysics such matters as space flights related to astronomy, lunar and planetary probes and satellites, meteorites and interplanetary matter, X rays and cosmic rays, quasars and pulsars. The abstracts are classified under more than one hundred subject categories thus permitting quick surveying of the bulk of material published on the same topic within six months. For instance, this volume records 119 papers on minor planets, 155 papers on supernovae, and 554 papers on cosmology.

Download or read book The Influence of Environment on the Properties of Galaxies written by Yasuhiro Hashimoto and published by . This book was released on 1998 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Paired and Interacting Galaxies written by International Astronomical Union. Colloquium and published by . This book was released on 1990 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Radio and Optical Properties of Radio Galaxies written by R. G. Hine and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Conference Publication written by and published by . This book was released on 1990 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quasars at All Cosmic Epochs written by Paola Marziani and published by Frontiers Media SA. This book was released on 2018-10-05 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last 50 years have seen a tremendous progress in the research on quasars. From a time when quasars were unforeseen oddities, we have come to a view that considers quasars as active galactic nuclei, with nuclear activity a coming-of-age experienced by most or all galaxies in their evolution. We have passed from a few tens of known quasars of the early 1970s to the 500,000 listed in the catalogue of the Data Release 14 of the Sloan Digital Sky Survey. Not surprisingly, accretion processes on the central black holes in the nuclei of galaxies — the key concept in our understanding of quasars and active nuclei in general — have gained an outstanding status in present-day astrophysics. Accretion produces a rich spectrum of phenomena in all bands of the electromagnetic spectrum. The power output of highly-accreting quasars has impressive effects on their host galaxies. All the improvement in telescope light gathering and in computing power notwithstanding, we still miss a clear connection between observational properties and theory for quasars, as provided, for example, by the H-R diagram for stars. We do not yet have a complete self-consistent view of nuclear activity with predictive power, as we do for main-sequence stellar sources. At the same time quasars offer many “windows open onto the unknown". On small scales, quasar properties depend on phenomena very close to the black hole event horizon. On large scales, quasars may effect evolution of host galaxies and their circum-galactic environments. Quasars’ potential to map the matter density of the Universe and help reconstruct the Universe’s spacetime geometry is still largely unexploited. The times are ripe for a critical assessment of our present knowledge of quasars as accreting black holes and of their evolution across the cosmic time. The foremost aim of this research topic is to review and contextualize the main observational scenarios following an empirical approach, to present and discuss the accretion scenario, and then to analyze how a closer connection between theory and observation can be achieved, identifying those aspects of our understanding that are still on a shaky terrain and are therefore uncertain knowledge. This research topic covers topics ranging from the nearest environment of the black hole, to the environment of the host galaxies of active nuclei, and to the quasars as markers of the large scale structure and of the geometry of spacetime of the Universe. The spatial domains encompass the accretion disk, the emission and absorption regions, circum-nuclear starbursts, the host galaxy and its interaction with other galaxies. Systematic attention is devoted to some key problems that remain outstanding and are clearly not yet solved: the existence of two quasar classes, radio quiet and radio loud, and in general, the systematic contextualization of quasar properties the properties of the central black hole, the dynamics of the accretion flow in the inner parsecs and the origin of the accretion matter, the quasars’ small and large scale environment, the feedback processes produced by the black hole into the host galaxy, quasar evolutionary patterns from seed black holes to the present-day Universe, and the use of quasars as cosmological standard candles. The timing is appropriate as we are now witnessing a growing body of results from major surveys in the optical, UV X, near and far IR, and radio spectral domains. Radio instrumentation has been upgraded to linear detector — a change that resembles the introduction of CCDs for optical astronomy — making it possible to study radio-quiet quasars at radio frequencies. Herschel and ALMA are especially suited to study the circum-nuclear star formation processes. The new generation of 3D magnetohydrodynamical models offers the prospective of a full physical modeling of the whole quasar emitting regions. At the same time, on the forefront of optical astronomy, applications of adaptive optics to long-slit spectroscopy is yielding unprecedented results on high redshift quasars. Other measurement techniques like 2D and photometric reverberation mapping are also yielding an unprecedented amount of data thanks to dedicated experiments and instruments. Thanks to the instrumental advances, ever growing computing power as well as the coming of age of statistical and analysis techniques, the smallest spatial scales are being probed at unprecedented resolution for wide samples of quasars. On large scales, feedback processes are going out of the realm of single-object studies and are entering into the domain of issues involving efficiency and prevalence over a broad range of cosmic epochs. The Research Topic "Quasars at all Cosmic Epochs" collects a large fraction of the contributions presented at a meeting held in Padova, sponsored jointly by the National Institute for Astrophysics, the Padova Astronomical Observatory, the Department of Physics and Astronomy of the University of Padova, and the Instito de Astrofísica de Andalucía (IAA) of the Consejo Superiór de Investigación Cientifica (CSIC). The meeting has been part of the events meant to celebrate the 250th anniversary of the foundation of the Padova Observatory.

Download or read book Literature 1988 Part 1 written by U. Esser and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1266 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 a 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#2