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Inferring The Photometric And Size Evolution Of Galaxies From Image Simulations
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Book Synopsis Inferring the Photometric and Size Evolution of Galaxies from Image Simulations by : Sébastien Carassou
Download or read book Inferring the Photometric and Size Evolution of Galaxies from Image Simulations written by Sébastien Carassou and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current constraints on the luminosity and size evolution of galaxies rely on catalogs extracted from multi-band surveys. However resulting catalogs are altered by selection effects difficult to model and that can lead to conflicting predictions if not taken into account properly. In this thesis we have developed a new approach to infer robust constraints on model parameters. We use an empirical model to generate a set of mock galaxies from physical parameters. These galaxies are passed through an image simulator emulating the instrumental characteristics of any survey and extracted in the same way as from observed data for direct comparison. The difference between mock and observed data is minimized via a sampling process based on adaptive Monte Carlo Markov Chain methods. Using mock data matching most of the properties of a Canada-France-Hawaii Telescope Legacy Survey Deep (CFHTLS Deep) field, we demonstrate the robustness and internal consistency of our approach by inferring the size and luminosity functions and their evolution parameters for realistic populations of galaxies. We compare our results with those obtained from the classical spectral energy distribution (SED) fitting method, and find that our pipeline infers the model parameters using only 3 filters and more accurately than SED fitting based on the same observables. We then apply our pipeline to a fraction of a real CFHTLS Deep field to constrain the same set of parameters in a way that is free from systematic biases. Finally, we highlight the potential of this technique in the context of future surveys and discuss its drawbacks.
Book Synopsis Deep Millimeter Surveys: Implications For Galaxy Formation And Evolution by : David H Hughes
Download or read book Deep Millimeter Surveys: Implications For Galaxy Formation And Evolution written by David H Hughes and published by World Scientific. This book was released on 2001-10-29 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: The arrival of large submillimeter and millimeter-wave detector arrays opened a new window on galaxy formation and evolution. The major new facilities now being designed or constructed, such as ALMA (MMA) and the Large Millimeter Telescope (LMT), will soon be expanding the horizons even farther.The Conference on “Deep Millimeter Surveys: Implications for Galaxy Formation and Evolution” drew together the major international groups working on submillimeter and millimeter-wave galaxies to discuss their relation to other galaxies both near by and in the early Universe, the role of the LMT and other new facilities in advancing the new field, and the implications of the new results and models for our understanding of galaxy formation and evolution. The resulting compendium of reports on observations, simulations, theory and interpretation, and instrumentation is the first book to present the new millimeter view of the early Universe thoroughly in a single volume.
Book Synopsis Galaxy Formation and Evolution by : Hyron Spinrad
Download or read book Galaxy Formation and Evolution written by Hyron Spinrad and published by Springer Science & Business Media. This book was released on 2006-08-29 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: An Astronomical Life – Observing the Depths of the Universe” Though science as a subject can be di?cult, what has been more important for me is that its practice can also be rewarding fun! This book is crafted to expose the reader to the excitement of modern observational cosmology through the study of galaxy evolution over space and cosmic time. Recent extragalactic research has led to many rapid advances in the ?eld. Even a suitable skeptic of certain pronouncements about the age and structure of the Universe should be pleased with the large steps that have been taken in furthering our understanding of the Universe since the early 1990’s. My personal involvement in galaxy research goes back to the 1960’s. At that point, galaxies were easily recognized and partially understood as organized c- lections of stars and gas. What their masses were presented a problem, which I supposed would just fade away. But fade it didn’t. Distant active nuclei and quasars were discovered in the mid-1960’s. A c- mon view of QSOs was that they have large redshifts, but what use are they for cosmology or normal galaxy astrophysics? I shared that conclusion. My expec- tions fell below their potential utility. In short, the Universe of our expectations rarely matches the Universe as it is discovered.
Book Synopsis The Evolution of Galaxies by : Marc Sauvage
Download or read book The Evolution of Galaxies written by Marc Sauvage and published by Springer Science & Business Media. This book was released on 2002-07-31 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies have a history. This has become clear from recent sky surveys which have shown that distant galaxies, formed early in the life of the Universe, differ from the nearby ones. New observational windows at ultraviolet, infrared and millimetric wavelengths (provided by ROSAT, IRAM, IUE, IRAS, ISO) have revealed that galaxies contain a wealth of components: very hot gas, atomic hydrogen, molecules, dust, dark matter ... A significant advance is expected due to new instruments (VLT, FIRST, XMM) which will allow one to explore the most distant Universe. Three Euroconferences have been planned to punctuate this new epoch in galactic research, bringing together specialists in various fields of Astronomy. The first one, held in Granada (Spain) in May 2000, addressed the observational clues. The second one took place in October 2001 in St Denis de la Réunion (France) and reviewed the basic building blocks and small-scale processes in galaxy evolution. The third one will take place in July 2002 in Kiel (Germany) and will be devoted to the overall modelling of galaxy evolution. This book contains the proceedings of the second conference. It is suitable for researchers and PhD students in Astrophysics.
Book Synopsis Dynamical Evolution of Galaxies by : Xiaolei Zhang
Download or read book Dynamical Evolution of Galaxies written by Xiaolei Zhang and published by Walter de Gruyter GmbH & Co KG. This book was released on 2017-12-04 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research monograph presents a new dynamical framework for the study of secular morphological evolution of galaxies along the Hubble sequence. Classical approaches based on Boltzmann’s kinetic equation, as well as on its moment-equation descendants the Euler and Navier-Stokes fluid equations, are inadequate for treating the maintenance and long-term evolution of systems containing self-organized structures such as galactic density-wave modes. A global and synthetic approach, incorporating correlated fluctuations of the constituent particles during a nonequilibrium phase transition, is adopted to supplement the continuum treatment. The cutting-edge research combining analytical, N-body simulational, and observational aspects, as well as the fundamental-physics connections it provides, make this work a valuable reference for researchers and graduate students in astronomy, astrophysics, cosmology, many-body physics, complexity theory, and other related fields. Contents Dynamical Drivers of Galaxy Evolution N-Body Simulations of Galaxy Evolution Astrophysical Implications of the Dynamical Theory Putting It All Together Concluding Remarks Appendix: Relation to Kinetics and Fluid Mechanics
Book Synopsis The Macro and Micro of Cosmic Dust by : Sidney Lower
Download or read book The Macro and Micro of Cosmic Dust written by Sidney Lower and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a comprehensive study of galaxy formation and evolution, beginning with understanding the origin of massive galaxies in the early Universe and ending with understanding the challenges in modeling spectro-photometric data to infer galaxy physical properties. Building on a long legacy of numerical effort to model galaxies, we use hydrodynamic cosmological simulations to predict the formation of the first massive galaxies, focusing on their star formation and chemical enrichment. We then use these simulations to ground-truth several commonly used models in the literature to infer galaxy properties from observables. The cosmological simulations, in combination with post-process radiative transfer, allow us to bridge the gap between theory and observation and holistically understand galaxy formation from both sides of the equation.
Book Synopsis Bulges and Disks in the Nearby Universe: Applications to Evolution and Formation of Galaxies by : Alan Meert
Download or read book Bulges and Disks in the Nearby Universe: Applications to Evolution and Formation of Galaxies written by Alan Meert and published by . This book was released on 2015-03-19 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Physics of Galaxy Formation by : Claudia Del P. Lagos
Download or read book The Physics of Galaxy Formation written by Claudia Del P. Lagos and published by Springer Science & Business Media. This book was released on 2013-10-15 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis addresses two of the central processes which underpin the formation of galaxies: the formation of stars and the injection of energy into the interstellar medium from supernovae, called feedback. In her work Claudia Lagos has completely overhauled the treatment of these processes in simulations of galaxy formation. Her thesis makes two major breakthroughs, and represents the first major steps forward in these areas in more than a decade. Her work has enabled, for the first time, predictions to be made which can be compared against new observations which probe the neutral gas content of galaxies, opening up a completely novel way to constrain the models. The treatment of feedback from supernovae, and how this removes material from the interstellar medium, is also likely to have a lasting impact on the field. Claudia Lagos Ph.D. thesis was nominated by the Institute for Computational Cosmology at Durham University as an outstanding Ph.D. thesis 2012.
Book Synopsis Galaxy Evolution Insights from Spectral Modeling of Large Data Sets from the Sloan Digital Sky Survey by :
Download or read book Galaxy Evolution Insights from Spectral Modeling of Large Data Sets from the Sloan Digital Sky Survey written by and published by . This book was released on 2007 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis centers on the use of spectral modeling techniques on data from the Sloan Digital Sky Survey (SDSS) to gain new insights into current questions in galaxy evolution. The SDSS provides a large, uniform, high quality data set which can be exploited in a number of ways. One avenue pursued here is to use the large sample size to measure precisely the mean properties of galaxies of increasingly narrow parameter ranges. The other route taken is to look for rare objects which open up for exploration new areas in galaxy parameter space. The crux of this thesis is revisiting the classical Kennicutt method for inferring the stellar initial mass function (IMF) from the integrated light properties of galaxies. A large data set (H"105 galaxies) from the SDSS DR4 is combined with more in-depth modeling and quantitative statistical analysis to search for systematic IMF variations as a function of galaxy luminosity. Galaxy H[alpha] equivalent widths are compared to a broadband color index to constrain the IMF. It is found that for the sample as a whole the best fitting IMF power law slope above 0.5 M{sub {circle_dot}} is [Lambda] = 1.5 ± 0.1 with the error dominated by systematics. Galaxies brighter than around M{sub r,0.1} = -20 (including galaxies like the Milky Way which has M{sub r,0.1} H"-21) are well fit by a universal [Lambda] H"1.4 IMF, similar to the classical Salpeter slope, and smooth, exponential star formation histories (SFH). Fainter galaxies prefer steeper IMFs and the quality of the fits reveal that for these galaxies a universal IMF with smooth SFHs is actually a poor assumption. Related projects are also pursued. A targeted photometric search is conducted for strongly lensed Lyman break galaxies (LBG) similar to MS1512-cB58. The evolution of the photometric selection technique is described as are the results of spectroscopic follow-up of the best targets. The serendipitous discovery of two interesting blue compact dwarf galaxies is reported. These galaxies were identified by their extremely weak (
Book Synopsis Unveiling Galaxies by : Jean-René Roy
Download or read book Unveiling Galaxies written by Jean-René Roy and published by Cambridge University Press. This book was released on 2018 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thought provoking study of the powerful impact of images in guiding astronomers' understanding of galaxies through time.
Book Synopsis Cosmic Evolution by : Eric J. Chaisson
Download or read book Cosmic Evolution written by Eric J. Chaisson and published by Harvard University Press. This book was released on 2001-02-16 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chaisson addresses some of the most basic issues we can contemplate: the origin of matter and the origin of life, and the ways matter, life, and radiation interact and change with time. He designs for us an expansive yet intricate model depicting the origin and evolution of all material structures.
Book Synopsis Galaxy Formation and Evolution by : Houjun Mo
Download or read book Galaxy Formation and Evolution written by Houjun Mo and published by Cambridge University Press. This book was released on 2010-05-20 with total page 841 pages. Available in PDF, EPUB and Kindle. Book excerpt: A coherent introduction for researchers in astronomy, particle physics, and cosmology on the formation and evolution of galaxies.
Book Synopsis Comparing Simulations and Observations of Galaxy Evolution by : Cameron Bryce Hummels
Download or read book Comparing Simulations and Observations of Galaxy Evolution written by Cameron Bryce Hummels and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: First, we create a method for producing synthetic photometric images of grid-based hydrodynamical models for use in a direct comparison against observations in a variety of filter bands. We apply this method to a simulation of a cluster of galaxies to investigate the nature of the red-sequence/blue-cloud dichotomy in the galaxy color-magnitude diagram. Second, we implement several subgrid models governing the complex behavior of gas and stars on small scales in our galaxy models. Several numerical simulations are conducted with similar initial conditions, where we systematically vary the subgrid models, afterward assessing their efficacy through comparisons of their internal kinematics with observed systems. Third, we generate an additional method to compare observations with simulations, focusing on the tenuous circumgalactic medium. Informed by our previous studies, we investigate the sensitivity of this new mode of comparison to hydrodynamical subgrid prescription. Finally, we synthesize the results of these studies and identify future avenues of research.
Book Synopsis The primordial universe - L'univers primordial by : P. Binetruy
Download or read book The primordial universe - L'univers primordial written by P. Binetruy and published by Springer Science & Business Media. This book was released on 2007-07-03 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews the interconnection of cosmology and particle physics over the last decade. It provides introductory courses in supersymmetry, superstring and M-theory, responding to an increasing interest to evaluate the cosmological consequences of these theories. Based on a series of extended courses providing an introduction to the physics of the very early universe, in the light of the most recent advances in our understanding of the fundamental interactions, it reviews all the classical issues (inflation, primordial fluctuations, dark matter, baryogenesis), but also introduces the most recent ideas about what happened at the Big Bang, and before.
Book Synopsis Influence of Surface Brightness and Size Constraints on Galaxy Survey Counts and Evolution by : Michael James Dorris
Download or read book Influence of Surface Brightness and Size Constraints on Galaxy Survey Counts and Evolution written by Michael James Dorris and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the formation and evolution of structure in the universe requires accurate quantification of populations of galaxies. The traditional single-variable luminosity function that has been used to quantify galaxy populations has been found lacking because the galaxy luminosity function has major discrepancies between surveys. Many authors have sought to resolve these discrepancies by finding correlations with other galaxy properties. Thus, galaxy statistics are increasingly being recast as multivariate functions. Here we make the case for one such popular function -- a bivariate brightness function in luminosity and surface brightness. To recover actual galaxy counts survey limits must be consistently applied in the same quantities used to construct the statistic. In particular, surface brightness is a natural second variable to use because the criteria used to select objects from an astronomical image are typically surface brightness and size. We construct a model for predicting the number of galaxies observed as a function of redshift and morphological type, excluding effects of evolution. We illustrate the effect upon galaxy counts due to the inclusion of surface brightness bias compared to the inclusion of the cosmological K-correction, the robustness of the method against uncertainty in the bivariate brightness function parameters, and the sensitivity of the expected galaxy counts to survey limits. Comparing observation against our no-evolution model can then yield evolution effects as a function of galaxy morphology -- if we can reliably classify galaxy morphology for large surveys. We focus on methods that can be applied directly to existing photometric catalogs, using the GOODS ACS data set to illustrate our methods. We first consider an attempt to directly extract galaxy morphology by means of a "concentration index'' calculated from aperture photometry. We find this method lacking in discriminatory power and dominated by significant error both in the base aperture photometry and in the fits derived thereof. This classification scheme we then compare to one derived from using a new neural network technique, Spatial Relational Learning. This algorithm not only produces error-free learning based upon the most closely biological neural model to date, but also allows for the extraction of classification rules rather than mere use as a "black box.'' We find that a simple two-variable classification scheme of b-v color and a best-fit Gaussian FWHM parameter, already a standard output of the most commonly used photometric extraction pipeline software, provides highly reasonable morphological classification. With this in hand, we can consider the task of extracting redshift distributions by morphological type from existing photometric catalogs to compare against our no-evolution models. In the case of the GOODS ACS data, we find evidence of significantly faster and more recent evolution among early-type, elliptical galaxies than late-type, disk galaxies. We then turn to consider the Sloan Digital Sky Survey; aside from its massive statistical potential, we consider Sloan because it also gives us the opportunity to explicate the use of non-isophotal detection limits and their effect upon the procedure we have laid out thus far. However, we show that even beyond the problem of shallower redshift coverage (and uncertainty in photometric redshifts), the SDSS is not well-suited for an analysis of this type. A galaxy survey must have a reasonably well-defined set of characteristic survey limits drawn from the actual detection pipeline in order to be useful for our no-evolution model. Nevertheless, even a relatively crude isophotal approximation to survey detection limits illustrates both the robustness of our approach and the pitfalls of morphology-sensitive selection criteria for object detection. Finally, in reviewing the history of hierarchical structure formation theory, our results suggest that the differing evolution epochs observed in the GOODS data argue away from the classical concept of one morphological type of galaxies evolving into another (e.g. via mergers) and more toward morphology-dependent physical processes. In particular we find for disk galaxies, long formation times for the thin disk structure, and for elliptical galaxies, star formation rate suppression and morphological shaping due to AGN-driven downsizing.
Book Synopsis The Origin and Evolution of Galaxies by : J.T. Jones
Download or read book The Origin and Evolution of Galaxies written by J.T. Jones and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Origin and Evolution of Galaxies is the outstanding problem of modern cosmology. Fortunately. we have a firm cosmological framework on which to base our theories (the hot big bang) and recently there has been substantial progress in providing observations which potentially can constrain these theories. The problem of galaxy formation is. as a consequence. one involving many diverse branches of physics and astrophysics. It has been the aim of the school. and this compendium of lectures and seminars. to bring together these diverse aspects at a level enabling research workers to understand what is going on in other corners of the subject and to see how progress in each area impinges on the others. We are grateful to the contributors to this volume for allowing us considerable editorial license with their articles. We have attempted to provide a representative sample of the talks that were given at the school besides the texts of the invited lecturers. It is regrettable that for reasons of space we have had to leave out a number of other contributions.
Book Synopsis The Realm of the Nebulae by : Edwin Powell Hubble
Download or read book The Realm of the Nebulae written by Edwin Powell Hubble and published by Yale University Press. This book was released on 1982-01-01 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: No modern astronomer made a more profound contribution to our understanding of the cosmos than did Edwin Hubble, who first conclusively demonstrated that the universe is expanding. Basing his theory on the observation of the change in distanct galaxies, called red shift, Hubble showed that this is a Doppler effect, or alteration in the wavelength of light, resulting from the rapid motion of celestial objects away from Earth. In 1935, Hubble described his principal observations and conclusions in the Silliman lectures at Yale University. These lectures were published the following year as "The Realm of the Nebulae," which quickly became a classic work.
