Download or read book High Redshift Star forming Galaxies in Absorption and Emission written by Anna Marie Quider and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Redshift Galaxies written by Immo Appenzeller and published by Springer Science & Business Media. This book was released on 2009-06-17 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: The high-redshift galaxies became a distinct research ?eld during the ?nal decade of the20thcentury. AtthattimetheLyman-breaktechniquemadeitpossibletoidentify signi?cant samples of such objects, and the new generation of 8 to 10-m telescopes resulted in ?rst good spectroscopic data. Today the high-redshift galaxies have developed into one of the important topics of astrophysics, accounting for about 5–10% of the publications in the major scienti?c journals devoted to astronomy. Because high-redshift galaxies is a rapidly developing ?eld and since new results are published constantly, writing a book on this topic is challenging. On the other hand, in view of the large amount of individual results now in the literature, and in view of the still growing interest in this topic, it appears worthwhile to summarize and evaluate the available data and to provide an introduction for those who wish to enter this ?eld, or who, for various reasons, might be interested in its results. The end of the ?rst decade of the 21st century appears to be a good point in time to attempt such a summary. The current generation of ground-based 8 to 10-m - optical telescopes, the Hubble Space Telescope, and the most important large radio telescopes have by now been in operation since about one or two decades. Although these instruments will continue to produce important scienti?c results for some time to come, many of the initial programs exploiting their unique new possibilities have been completed.

Download or read book Galaxies at High Redshift written by I. Pérez-Fournon and published by Cambridge University Press. This book was released on 2003-03-20 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents lectures of the XI Canary Islands Winter School of Astrophysics written by experts in the field.

Download or read book Astronomical Data Analysis Software and Systems X written by Frank Roderic Harnden and published by . This book was released on 2001 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Hubble Deep Field written by Space Telescope Science Institute (U.S.). Symposium and published by Cambridge University Press. This book was released on 1998-10-13 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Hubble Deep Field (HDF) is the deepest optical image of the Universe ever obtained. It is the result of a 150-orbit observing programme with the Hubble Space Telescope. It provides a unique resource for researchers studying the formation and evolution of stars and galaxies. This timely volume provides the first comprehensive overview of the HDF and its scientific impact on our understanding in cosmology. It presents articles by a host of world experts who gathered together at an international conference at the Space Telescope Science Institute. The contributions combine observations of the HDF at a variety of wavelengths with the latest theoretical progress in our understanding of the cosmic history of star and galaxy formation. The HDF is set to revolutionize our understanding in cosmology. This book therefore provides an indispensable reference for all graduate students and researchers in observational or theoretical cosmology.

Download or read book The Kiloparsec Scale Structure and Kinematics of High Redshift Star Forming Galaxies written by David R. Law and published by Universal-Publishers. This book was released on 2008-09 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the spatially resolved properties of star-forming galaxies at redshift z 2 - 3 on scales 1 kpc using a combination of morphological and kinematic analyses in an effort to characterize the major mechanisms of galaxy formation in the young universe. Using a sample of 216 galaxies which have been spectroscopically confirmed to lie between redshifts z = 1.8 - 3.4 in the GOODS-N field we demonstrate that rest-UV morphology (as seen by the Hubble Space Telescope) is statistically uncorrelated with physical properties such as star formation rate and is therefore unable to support the hypothesis that the prevalence of irregular morphologies indicates a high major merger fraction. Further, we present a sample of 13 galaxies observed with the OSIRIS integral field spectrograph and the Keck laser-guide star adaptive optics system which demonstrate the prevalence of high velocity dispersions 80 km/s and generally little in the way of spatially resolved velocity gradients, inconsistent with favored rotating disk models. We discuss the implications of these results for galaxy formation models, including gas accretion via cold flows and gravitational instability of early gas-rich galactic disks. There is some evidence for a trend towards stronger rotational signatures in galaxies with more massive stellar populations.

Download or read book Stellar Populations Outflows and Morphologies of High redshift Galaxies written by Katherine Anne Kornei and published by . This book was released on 2012 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the regulation and environment of star formation across cosmic time is critical to tracing the build-up of mass in the Universe and the interplay between the stars and gas that are the constituents of galaxies. Three studies are presented in this thesis, each examining a different aspect of star formation at a specific epoch. The first study presents the results of a photometric and spectroscopic survey of 321 Lyman break galaxies (LBGs) at z = 3 to investigate systematically the relationship between Ly & alpha; emission and stellar populations. Ly & alpha; equivalent widths were calculated from rest-frame UV spectroscopy and optical/near-infrared/Spitzer photometry was used in population synthesis modeling to derive the key properties of age, dust extinction, star formation rate (SFR), and stellar mass. We directly compare the stellar populations of LBGs with and without strong Ly & alpha; emission, where we designate the former group (Ly & alpha; equivalent widths greater than 20 & Aring;) as Ly & alpha;-emitters (LAEs) and the latter group (Ly & alpha; equivalent widths fewer than 20 & Aring;) as non-LAEs. This controlled method of comparing objects from the same UV luminosity distribution represents an improvement over previous studies in which the stellar populations of LBGs and narrowband-selected LAEs were contrasted, where the latter were often intrinsically fainter in broadband filters by an order of magnitude simply due to different selection criteria. Using a variety of statistical tests, we find that Ly & alpha; equivalent width and age, SFR, and dust extinction, respectively, are significantly correlated in the sense that objects with strong Ly & alpha; emission also tend to be older, lower in star formation rate, and less dusty than objects with weak Ly & alpha; emission, or the line in absorption. We accordingly conclude that, within the LBG sample, objects with strong Ly & alpha; emission represent a later stage of galaxy evolution in which supernovae-induced outflows have reduced the dust covering fraction. We also examined the hypothesis that the attenuation of Ly & alpha; photons is lower than that of the continuum, as proposed by some, but found no evidence to support this picture. The second study focuses specifically on galactic-scale outflowing winds in 72 star-forming galaxies at z = 1 in the Extended Groth Strip. Galaxies were selected from the DEEP2 survey and follow-up LRIS spectroscopy was obtained covering SiII, CIV, FeII, MgII, and MgI lines in the rest-frame ultraviolet. Using GALEX, HST, and Spitzer imaging available for the Extended Groth Strip, we examine galaxies on a per-object basis in order to better understand both the prevalence of galactic outflows at z = 1 and the star-forming and structural properties of objects experiencing outflows. Gas velocities, measured from the centroids of FeII interstellar absorption lines, are found to span the interval -217, +155 km s-1. We find that approximately 40% (10%) of the sample exhibits blueshifted FeII lines at the 1 & sigma; (3 & sigma;) level. We also measure maximal outflow velocities using the profiles of the FeII and MgII lines; we find that MgII frequently traces higher velocity gas than FeII. Using quantitative morphological parameters derived from the HST imaging, we find that mergers are not a prerequisite for driving outflows. More face-on galaxies also show stronger winds than highly inclined systems, consistent with the canonical picture of winds emanating perpendicular to galactic disks. In light of clumpy galaxy morphologies, we develop a new physically-motivated technique for estimating areas corresponding to star formation. We use these area measurements in tandem with GALEX-derived star-formation rates to calculate star-formation rate surface densities. At least 70% of the sample exceeds a star-formation rate surface density of 0.1 solar masses yr-1 kpc-2, the threshold necessary for driving an outflow in local starbursts. At the same time, the outflow detection fraction of only 40% in FeII absorption provides further evidence for an outflow geometry that is not spherically symmetric. We see a 3 & sigma; trend between outflow velocity and star-formation rate surface density, but no significant trend between outflow velocity and star-formation rate. Higher resolution data are needed in order to test the scaling relations between outflow velocity and both star-formation rate and star-formation rate surface density predicted by theory. Galactic winds are further explored in the third study of this thesis, where we present a study at z = 1 of the prevalence and kinematics of ultraviolet emission lines from fine-structure FeII* transitions and resonance MgII transitions. Utilizing a multiwavelength dataset of 212 star-forming galaxies, we investigate how the strength and kinematics of FeII* and MgII emission lines vary as a function of galaxy properties. We find that FeII* emission is prevalent in the sample; composite spectra assembled on the basis of a variety of galaxy properties all show FeII* emission, particularly in the stronger 2396 and 2626 & Aring; lines. This prevalence of emission is in contrast to observations of local galaxies; the lack of FeII* emission in the small star-forming regions targeted by spectroscopic observations at z = 0 may imply that FeII* emission arises in more extended galaxy halos. The strength of FeII* emission is most strongly modulated by star-formation rate, dust attenuation, and [OII] equivalent width, such that systems with lower star-formation rates, lower dust levels, and larger [OII] equivalent widths show stronger FeII* emission. MgII emission, while not observed in a spectral stack of all the data in our sample, is seen in 30% of individual objects. We find that objects showing MgII emission have preferentially larger [OII] equivalent widths, bluer U-B colors, and lower stellar masses than the sample as a whole. Active galactic nuclei are not likely responsible for the MgII emission in our sample, since we have excluded active galaxies from our dataset. We also do not observe the NeV emission line at 3425 & Aring; characteristic of active galaxies in our co-added spectra. We find that the kinematics of FeII* emission lines are consistent with the systemic velocity. This result does not necessarily imply that these lines arise from star-forming regions, however, as an optically thin galactic wind could show blueshifted and redshifted FeII* emission lines centered around 0 km s-1. We note that FeII* emission arising from extended gas is consistent with the hypothesis that slit losses are responsible for the lack of FeII* emission in local samples. We propose that dust is primarily responsible for the correlations between FeII* strength and galaxy properties, as objects with lower star-formation rates and larger [OII] equivalent widths also exhibit lower dust attenuations, on average. The strong MgII emission seen in systems with larger [OII] equivalent widths, bluer U-B colors, and lower stellar masses may also be the result of low dust attenuation in these objects. Larger studies composed of high signal-to-noise observations will be critical for testing the hypothesis that dust is the primary modulator of fine-structure and resonance emission.

Download or read book The Properties of Star Forming Galaxies at Z 2 written by Dawn Erb and published by Universal-Publishers. This book was released on 2005 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the properties of star-forming galaxies at redshift z 2, an era in which a substantial fraction of the stellar mass in the universe formed. Using 114 near-IR spectra of the H-alpha and [N II] emission lines and model spectral energy distributions fit to rest-frame UV through IR photometry, we examine the galaxies' star formation properties, dynamical masses and velocity dispersions, spatially resolved kinematics, outflow properties, and metallicities as a function of stellar mass and age. While the stellar masses of the galaxies in our sample vary by a factor of 500, dynamical masses from H-alpha velocity dispersions and indirect estimates of gas masses imply that the variation of stellar mass is due as much to the evolution of the stellar population and the conversion of gas into stars as to intrinsic differences in the total masses of the galaxies. About 10% of the galaxies are apparently young starbursts with high gas fractions, caught just as they have begun to convert large amounts of gas into stars. Using the [N II]/H-alpha ratio of composite spectra to estimate the average oxygen abundance, we find a monotonic increase in metallicity with stellar mass. From the estimated gas fractions, we conclude that the observed mass-metallicity relation is primarily driven by the increase in metallicity as gas is converted to stars. The picture that emerges is of galaxies with a broad range in stellar population properties, from young galaxies with ages of a few tens of Myr, stellar masses M 10 DEGREES9 Msun, and metallicities Z 1/3 Zsun, to massive objects with M* 10 DEGREES11 Msun, Z Zsun, and ages as old as the universe allows. All, however, are rapidly star-forming, power galactic-scale outflows, and have masses in gas and stars of at least 10 DEGREES10 Msun, in keeping with their likely role as the progenitors of elliptical galaxies

Download or read book Astrophysics Of Gas Nebulae and Active Galactic Nuclei written by Donald E. Osterbrock and published by University Science Books. This book was released on 2006 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thoroughly revised and expanded throughout, the new edition is a graduate-level text and reference book on gaseous nebulae, nova and supernova remnants. Much of the new data and new images are from the Hubble Space Telescope with two wholly new chapters being added along with other new features. The previous edition which was tried and tested for thirty years has now been succeeded by a revised, updated, larger edition, which will be valuable to anyone seriously interested in astrophysics.

Download or read book The Environment and Evolution of Galaxies written by J.M. Shull and published by Springer Science & Business Media. This book was released on 1993-10-31 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: In July 1992, over 300 astronomers attended the Third Tetons Summer School on the subject of `The Environment and Evolution of Galaxies'. This book presents 28 papers based on invited review talks and a panel discussion on `The Nature of High Redshift Objects'. The major themes include: the Interstellar and Intergalactic Medium, Galaxy Formation and Evolution, Cooling Flows, Quasars and Radiation Backgrounds, and Interactions between Galaxies/AGNs and their Environment. Recent advances with the ROSAT, COBE and Hubble Space Telescope are discussed, together with current theoretical developments. The tutorial nature of the papers make this book a valuable supplement for professional astonomers, graduate students, and senior undergraduates. As with previous Tetons conferences, this book provides both the current state of observational and theoretical research and material complementary to courses in extragalactic and interstellar astrophysics.

Download or read book Starburst Galaxies Near and Far written by L. Tacconi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: A major fraction of star formation in the universe occurs in starbursts. These regions of particularly rapid star formation are often located towards the centers of host galaxies. Studies of this kind of star formation at high redshift have produced astonishing results over recent years that were only possible with the latest generation of large ground-based and space telescopes. The papers collected in this volume present these results in the context of the much firmer foundation of star formation in the local universe, and they emphasize all the important topics, from star formation in different environments to the cosmic star formation history.

Download or read book Lyman Alpha Emitting Galaxies at High Redshift written by Steven Arthur Dawson and published by Universal-Publishers. This book was released on 2005 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: As late as 1995, the anticipated widespread population of primeval galaxies remained at large, lurking undetected at unknown redshifts, with undiscovered properties. We present results from our efforts to detect and characterize primeval galaxies by their signature high-redshift Lyman-alpha emission lines utilizing two observational techniques: serendipitous slit spectroscopy and narrowband imaging. By pushing these techniques to their utmost limits, we probe the Lyman-alpha-emitting galaxy population out to redshifts as high as z = 6.5. Galaxies at this epoch reside in a universe which is just 800 million years old, a mere 6% of its current age. As such, this work provides one account of the manner by which observational cosmology has recently shifted from merely marveling at the incredible lookback times implied by the first few high-redshift detections, to the routine assembly of high-redshift datasets designed to address specific astrophysical issues.

Download or read book Gamma ray Bursts as Probes of the High redshift Universe written by Jean-Baptiste Vielfaure and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les sursauts-gamma (GRBs) sont parmi les événements cosmiques les plus brillants. Ces flashs de photons gamma de courte durée sont suivis d'une rémanence brillante observable des rayons X aux ondes radio. La classe des sursauts-gamma longs (LGRBs) est associée à la mort d'étoiles massives. Les LGRBs se produisent généralement dans des galaxies peu brillantes avec des taux de formation stellaire spécifiques élevés et des environnements à métallicité inférieure à la métallicité solaire. Leurs hôtes pourraient être représentatifs de la population de galaxies présente à l'époque de la réionisation, encore mal connue. L'utilisation des LGRBs comme sondes des galaxies dans l'Univers distant offre des avantages uniques : (i) le flash de photons gamma nous permet de détecter des galaxies à tous décalages spectraux indépendamment de leurs propriétés d'émission; (ii) grâce à leur forte luminosité, les LGRBs peuvent être utilisés comme des phares capables de révéler le milieu interstellaire (MIS) des galaxies même les plus faibles et les plus éloignées, en apportant des détails inaccessibles autrement; (iii) la rémanence des LGRBs s'estompe rapidement, permettant l'étude des galaxies hôtes. Le but de cette thèse est d'utiliser les LGRBs pour étudier certaines des propriétés des galaxies à formation d'étoiles, distantes et faibles. Pour cela, je combine les informations sur le MIS obtenues par les raies d'absorption présentes dans les spectres de rémanence à celles du gaz ionisé obtenues par les raies d'émission de la galaxie hôte. De plus, j'approfondis l'interprétation des données à l'aide de simulations numériques.La première partie de cette thèse montre que les LGRBs sont des outils puissants pour détecter l'échappement de photons ionisants de galaxies très faibles et caractériser les voies par lesquelles cela se produit.Je présente les résultats de l'observation d'émission LyC dans le spectre de rémanence d'un LGRB nouvellement découvert. Cette détection est complétée par les observations de deux autres galaxies hôtes de LGRBs pour lesquelles un échappement de LyC est connu, afin de déterminer leur fraction d'échappement en LyC et de comparer leurs propriétés. Les fractions d'échappement calculées le long de la ligne de visée du LGRB sont élevées, et augmentent le nombre de détections des émetteurs LyC, en particulier à des magnitudes absolues très faibles.La deuxième partie de mon travail est consacrée à l'étude de la population des galaxies hôtes de LGRB étant émetteurs Lyman-alpha (LAE). Je mets à jour le recensement de ces galaxies en fournissant une compilation de toutes les détections disponibles, et en déterminant les statistiques de LAEs à partir d'échantillons spectroscopiques de galaxies hôtes de LGRB et de rémanences.A partir de cette étude, je sélectionne un sous-échantillon de quatre galaxies pour lesquelles on peut mesurer les principaux paramètres nécessaires pour contraindre le modèle de coquille utilisé pour interpréter la raie d'émission Lyman-alpha.Le modèle donne des résultats inconsistants pour les LGRB-LAEs qui présentent les densités de colonne d'hydrogène neutre les plus élevées, pourtant typiques des hôtes de LGRB et des LGRB-LAEs.Ce résultat amène à une interprétation des informations sondées le long de la ligne de visée des LGRBs et de l'échappement des photons Lya. Enfin, ces résultats sont approfondis à travers la simulation numérique d'une galaxie à z=3 ayant des propriétés typiques des galaxies hôtes de LGRB. Je trouve que les photons Lyman-alpha s'échappent de plusieurs régions au sein de la galaxie plutôt que d'une seule région dominante jeune et active qui pourrait héberger le LGRB. Cette thèse montre que les observations de la rémanence des LGRBs et de leur galaxie hôte sont des outils puissants permettant d'explorer les propriétés des galaxies faibles et distantes.

Download or read book High Redshift and Primeval Galaxies written by Jacqueline Bergeron and published by Atlantica Séguier Frontières. This book was released on 1987 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Panchromatic View of Galaxies written by Alessandro Boselli and published by John Wiley & Sons. This book was released on 2012-01-17 with total page 343 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describing how to investigate all kinds of galaxies through a multifrequency analysis, this text is divided into three different sections. The first describes the data currently available at different frequencies, from X-rays to UV, optical, infrared and radio millimetric and centimetric, while explaining their physical meaning. In the second section, the author explains how these data can be used to determine physical parameters and quantities, such as mass and temperature. The final section is devoted to describing how the derived quantities can be used in a multifrequency analysis to study such physical processes as the star formation cycle and constrain models of galaxy evolution. As a result, observers will be able to interpret galaxies and their structure.

Download or read book The Road to Galaxy Formation written by William C. Keel and published by Springer Science & Business Media. This book was released on 2002-09-20 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by one of the leading authorities in the field, this is one of the first book's to describe one of today's most important problems in cosmology - the formation of galaxies. The book tackles this great puzzle by discusses the beginnings of the process from cosmological observations and calculations, considers the broad features of galaxies that we need to explain and what we know of their later history. The author compares the competing theories for galaxy formation and considers the progress expected from new generations of powerful telescopes both on earth and in space. An intriguing text on one of today's greatest and most profound puzzles.

Download or read book How Did the First Stars and Galaxies Form written by Abraham Loeb and published by Princeton University Press. This book was released on 2010-07-19 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: A concise introduction to cosmology and how light first emerged in the universe Though astrophysicists have developed a theoretical framework for understanding how the first stars and galaxies formed, only now are we able to begin testing those theories with actual observations of the very distant, early universe. We are entering a new and exciting era of discovery that will advance the frontiers of knowledge, and this book couldn't be more timely. It covers all the basic concepts in cosmology, drawing on insights from an astronomer who has pioneered much of this research over the past two decades. Abraham Loeb starts from first principles, tracing the theoretical foundations of cosmology and carefully explaining the physics behind them. Topics include the gravitational growth of perturbations in an expanding universe, the abundance and properties of dark matter halos and galaxies, reionization, the observational methods used to detect the earliest galaxies and probe the diffuse gas between them—and much more. Cosmology seeks to solve the fundamental mystery of our cosmic origins. This book offers a succinct and accessible primer at a time when breathtaking technological advances promise a wealth of new observational data on the first stars and galaxies. Provides a concise introduction to cosmology Covers all the basic concepts Gives an overview of the gravitational growth of perturbations in an expanding universe Explains the process of reionization Describes the observational methods used to detect the earliest galaxies