Advanced technologies in astronomy at various wavelengths have provided us with high resolution and high quality data on the QSO population. This meeting was aimed at understanding the morphology and nature of the host galaxies and environments of QSOs. The invited lectures as well as the contributed and poster papers highlighted the main issues of current research: the stellar and gaseous content of the underlying galaxy; the characterization of the population of companions and the nature of their interaction with the host galaxy; the connection between radio-loud QSO and radio-galaxies, and QSOs and ULIRGs; the evolution with redshift of both the host galaxy and its environment, and the main implications in theories of galaxy formation and evolution. This volume provides a valuable overview and timely update of the exciting and rapidly developing field of QSO hosts and their environments - essential reading for graduate students and researchers.

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.

This edited volume presents the current state of gas accretion studies from both observational and theoretical perspectives, and charts our progress towards answering the fundamental yet elusive question of how galaxies get their gas. Understanding how galaxies form and evolve has been a central focus in astronomy for over a century. These studies have accelerated in the new millennium, driven by two key advances: the establishment of a firm concordance cosmological model that provides the backbone on which galaxies form and grow, and the recognition that galaxies grow not in isolation but within a “cosmic ecosystem” that includes the vast reservoir of gas filling intergalactic space. This latter aspect in which galaxies continually exchange matter with the intergalactic medium via inflows and outflows has been dubbed the “baryon cycle”. The topic of this book is directly related to the baryon cycle, in particular its least well constrained aspect, namely gas accretion. Accretion is a rare area of astrophysics in which the basic theoretical predictions are established, but the observations have been as yet unable to verify the expectations. Accretion has long been seen around the Milky Way in so-called High Velocity Clouds, but detecting accretion even around nearby galaxies has proved challenging; its multi-phase nature requires sensitive observations across the electromagnetic spectrum for full characterization. A promising approach involves looking for kinematic signatures, but accretion signatures are often confused with internal motions within galaxies. Accretion studies therefore touch a wide range of astrophysical processes, and hence a wide cross-section of the astronomical community. As observational facilities are finally able to access the wavelength ranges and depths at which accretion processes may be manifest, the time is right to survey these multiple lines of investigation and determine the state of the field in accretion studies of the baryon cycle.

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.

"Astrophysics Updates" is intended to serve the information needs of professional astronomers and postgraduate students about areas of astronomy, astrophysics and cosmology that are rich and active research spheres. Observational methods and the latest results of astronomical research are presented as well as their theoretical foundations and interrelations. The contributed commissioned articles are written by leading exponents in a format that will appeal to professional astronomers and astrophysicists who are interested in topics outside their own specific areas of research. This collection of timely reviews may also attract the interest of advanced amateur astronomers seeking scientifically rigorous coverage.

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

This book was originally published in 2004. Black holes are among the most mysterious objects in the Universe. Weighing up to several billion Suns, massive black holes have long been suspected to be the central powerhouses of energetic phenomena such as quasars. Advances in astronomy have not only provided spectacular proof of this long-standing paradigm, but have revealed the unexpected result that far from being rare, exotic beasts, they inhabit the center of virtually all large galaxies. Candidate black holes have been identified in increasingly large numbers of galaxies, both inactive and active, to the point where statistical studies are possible. Fresh work has highlighted the close connection between the formation, growth, and evolution of supermassive black holes and their host galaxies. This volume contains the invited lectures from an international symposium that was held to explore this exciting theme, and is a valuable review for professional astronomers and graduate students.

This book acknowledges the importance of identifying the most crucial science to be performed by the superb Hubble Telescope. With this goal in mind, the book presents a review of some of the most important open questions in astronomy. World experts examine topics ranging from extrasolar planets and star formation to supermassive black holes and the reionization of the universe. Special emphasis is placed on what astronomical observations should be carried out during the next few years to enable breakthroughs in our understanding of a complex and dynamic universe. In particular, the reviewers attempt to identify those topics to which the Hubble Space Telescope can uniquely contribute. The special emphasis on future research makes this book an essential resource for both professional researchers and graduate students in astronomy and astrophysics.