Download or read book Ultraluminous Infrared Galaxies and the Radio optical Correlation for Quasars written by Carol J. Lonsdale Persson and published by . This book was released on 19?? with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book X ray Optical and Infrared Luminosity Correlations in Radio quiet Quasars written by Gerard A. Kriss and published by . This book was released on 1987 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A High Resolution Optical near infrared Study of the Evolutionary Link Between Ultraluminous Infrared Galaxies and Optical QSOs written by Jason A. Surace and published by . This book was released on 1998 with total page 584 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 Dust in Radio Quiet Quasars Ultra Luminous Infrared Galaxies Radio Galaxies and Radio Loud Quasars written by Sven Archibald Hubertus Müller and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of the Optical and X ray Properties of Quasars written by Steven Ever Bradley and published by . This book was released on 1985 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Origin of the Radio Emission of Ultraluminous Infrared Galaxies written by 張敏悌 and published by . This book was released on 2005 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Radio and Optical Luminosity Evolution of Quasars written by and published by . This book was released on 2011 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux limited data set containing 636 quasars with radio and optical fluxes from White et al. We first note that when dealing with multivariate data it is imperative to first determine the true correlations among the variables, not those introduced by the observational selection effects, before obtaining the individual distributions of the variables. We use the methods developed by Efron and Petrosian which are designed to obtain unbiased correlations, distributions, and evolution with redshift from a data set truncated due to observational biases. It is found that as expected the population of quasars exhibits strong positive correlation between the radio and optical luminosities and that this correlation deviates from a simple linear relation in a way indicating that more luminous quasars are more radio loud. We also find that there is a strong luminosity evolution with redshift in both wavebands, with significantly higher radio than optical evolution. We conclude that the luminosity evolution obtained by arbitrarily separating the sources into radio loud (R> 10) and radio quiet (R
Download or read book The Optical Infrared and Radio Properties of Extragalactic Sources Observed by SDSS 2mass and First Surveys written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We positionally match sources observed by the Sloan Digital Sky Survey (SDSS), the Two Micron All Sky Survey (2MASS), and the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey. Practically all 2MASS sources are matched to an SDSS source within 2 arcsec;[approx] 11% of them are optically resolved galaxies and the rest are dominated by stars. About 1/3 of FIRST sources are matched to an SDSS source within 2 arcsec;[approx] 80% of these are galaxies and the rest are dominated by quasars. Based on these results, we project that by the completion of these surveys the matched samples will include about 10[sup 7] and 10[sup 6] galaxies observed by both SDSS and 2MASS, and about 250,000 galaxies and 50,000 quasars observed by both SDSS and FIRST. Here we present a preliminary analysis of the optical, infrared and radio properties for the extragalactic sources from the matched samples. In particular, we find that the fraction of quasars with stellar colors missed by the SDSS spectroscopic survey is probably not larger than[approx] 10%, and that the optical colors of radio-loud quasars are[approx] 0.05 mag. redder (with 4[sigma] significance) than the colors of radio-quiet quasars.
Download or read book Fifty Years of Quasars written by Mauro D'Onofrio and published by Springer Science & Business Media. This book was released on 2012-09-14 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 50th anniversary of the discovery of quasars in 1963 presents an interesting opportunity to ask questions about the current state of quasar research. Formatted as a series of interviews with noted researchers in the field, each of them asked to address a specific set of questions covering topics selected by the editors, this book deals with the historical development of quasar research and discusses how advances in instrumentation and computational capabilities have benefitted quasar astronomy and have changed our basic understanding of quasars. In the last part of the book the interviews address the current topic of the role of quasars in galaxy evolution. They summarise open issues in understanding active galactic nuclei and quasars and present an outlook regarding what future observational facilities both on the ground and in space might reveal. Its interview format, the fascinating topic of quasars and black holes, and the lively recollections and at times controversial views of the contributors make this book both rewarding and a pleasure to read!
Download or read book Literature 1991 Part 2 written by Astronomisches Rechen-Institut and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 1592 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Astronomy and Astrophysics Abstracts" appearing twice a year has become oneof the fundamental publications in the fields of astronomy, astrophysics andneighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. The abstrats 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.
Download or read book Quasars and Active Galactic Nuclei written by Marshall Harris Cohen and published by . This book was released on 1995 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Probing Quasar Accretion Physics with Optical and X ray Spectroscopy written by Monica Young and published by . This book was released on 2011 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Black holes, lurking at the centers of distant galaxies, feed on gas to become quasars. The bulk of the powerful emission from radio-quiet quasars originates from two structures close to the central black hole: the accretion disk and the hot corona. The disk-corona relationship and its dependence on the rate of gas accretion onto the central black hole is not well understood, in part because of the lack of knowledge regarding the corona temperature, density and geometry. To gain a better understanding of the accretion physics that affect the growth and evolution of quasars, as well as the evolution of their host galaxies, I perform a large-scale study of quasar optical through X-ray spectral energy distributions (SED). I have cross-correlated optical DR5 Sloan Digital Sky Survey (SDSS) quasars with the XMM-Newton archive of X-ray observations to obtain 792 optically-selected quasars with X-ray observations, 473 of which have X-ray spectra. I investigate relations between accretion rate, optical and X-ray luminosity, and X-ray slope. I compare the observed correlations with population synthesis simulations to determine which correlations are intrinsic to the physics of quasar accretion, and which are simply due to selection effects or the consequence of another correlation. I discuss the results with respect to physical models. At low accretion rates, the disk-corona structure may change significantly. I investigate this possibility in the case of red quasars by using optical and X-ray information to disentangle the effect of absorption and low accretion rates on red quasar SEDs. I find that 7 out of 17 of the reddest SDSS quasars are not well described by absorption. Instead, the red optical colors appear to be intrinsic to the accretion physics, and are perhaps related to the low accretion rates ( L/L Edd -0.05) observed for these objects. By extending the intrinsically red quasar SEDs to the infrared and ultraviolet wavelengths, I constrain standard disk models. By combining studies of large-scale trends with case studies of quasar accretion under extreme conditions, I investigate current models of disk-corona interactions.
Download or read book From Merging Galaxies to Quasars written by Stacy H. Teng and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Infrared View of the Coevolution of Massive Blackholes and Galaxies written by Yong Shi and published by . This book was released on 2008 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Massive blackhole (MBH) growth is now recognized as a critical ingredient of galaxy formation and evolution. To investigate the interplay between MBH growth and galaxy evolution, we have used the capabilities of the Spitzer Space Telescope to study active galactic nuclei (AGN) and luminous infrared galaxies. We have tested the unification model for radio-loud AGN by finding that radio quasars and some FRII radio galaxies follow a correlation between low-frequency radio and the 70 um emission, two presumably isotropic indicators of nuclear radiation. We have found that mid-IR obscuration (characterized by the strength of the silicate feature) correlates with the X-ray obscuration (characterized by the HI column density), such that low HI columns correspond to silicate emission while high columns correspond to silicate absorption, for various types of AGN. We have demonstrated that in situ electron acceleration is required for both jet and lobe emission in M87. We have measured aromatic features in local AGN, demonstrated the diverse nature (star formation vs. AGN) of the far-IR emission mechanism, and constructed the star formation luminosity functions of the AGN hosts. These luminosity functions are flatter than that of field galaxies, implying that the interplay between star formation and nuclear activity enhances both processes. For luminous infrared galaxies (LIRGs), we have characterized galaxy morphologies of a complete sample of LIRGs at z1̃ and found that LIRGs at z1̃ are as asymmetric as local ones, implying similar conditions within galaxies lead to a LIRG level of star formation.
Download or read book Physics Briefs written by and published by . This book was released on 1993 with total page 1288 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 1987 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt:
